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Elabore 1 pregunta de ensayo sobre los canales del marketing internacional basado en lo siguiente:

Estructuras del canal de distribución.

Para que una compañía alcance sus metas de marketing, su producto debe estar a disposición del mercado meta a un precio accesible. Llevar el producto al mercado meta puede ser un proceso muy costoso si no supera las fallas que pudiera haber en su estructura de distribución. La tarea más crítica y desafiante que podría afrontar la compañía internacional es forjar un canal de distribución dinámico y confiable. Es más, algunas voces dicen que afrontar estos desafíos es un catalizador fundamental para el desarrollo económico. Cada mercado contiene una red de distribución que ofrece la opción de muchos canales con estructuras únicas y, a corto plazo, fijas. En algunos mercados, la estructura de distribución consta de muchos estratos y es compleja, ineficiente o incluso extraña, y con frecuencia las compañías vendedoras nuevas tienen dificultad para entrar en ella; en otros, existen pocos intermediarios especializados, salvo en las grandes zonas urbanas; pero otros más, ofrecen una mezcla dinámica y cambiante de sistemas de distribución tradicionales y nuevos a escala global. Sea cual fuere la estructura de distribución predominante, la ventaja competitiva será para la compañía que consiga crear los canales más eficientes con base en las alternativas que tiene a su disposición. Además, a medida que el comercio global siga floreciendo en el siglo xxi, y que las infraestructuras para la distribución física se rezaguen, los desafíos serán incluso más grandes. Este capítulo aborda los puntos básicos que incluye la toma de decisiones relativas al canal: las estructuras de los canales; los patrones de la distribución; las alternativas de intermediarios existentes; los factores que afectan la elección de canales, y el modo de encontrar, seleccionar y motivar a los intermediarios, así como la manera de finalizar su contrato. Estructuras del canal de distribución En cada país y en cada mercado, sea urbano o rural, rico o pobre, todos los productos de consumo y los industriales en algún momento deben pasar por un proceso de distribución. El proceso de distribución incluye el manejo y la distribución físicos de los bienes, el cambio de posesión (título de propiedad) y, lo más importante desde el punto de vista de la estrategia de marketing, las negociaciones para la compraventa que llevan a cabo los productores y los intermediarios, y los intermediarios y los clientes. El gerente de marketing internacional afronta innumerables cuestiones políticas y estratégicas para la elección de los canales. Estas cuestiones no son muy diferentes de las que el gerente enfrenta para la distribución interna en su país, pero las debe resolver de otra manera porque los patrones de los mercados y las alternativas para los canales son diferentes. El mercado de cada país tiene una estructura de distribución para que los bienes pasen del productor al usuario. Esta estructura contiene una serie de intermediarios que suelen desempeñar funciones, actividades y servicios que reflejan la competencia existente, las características del mercado, las tradiciones y el desarrollo económico. En pocas palabras, la conducta de los miembros del canal es resultado de las interacciones entre el entorno cultural y el proceso del marketing. Las estructuras de los canales van desde aquellas en las que no hay mucha infraestructura desarrollada para el marketing, como la que existe en muchos mercados emergentes, hasta el muy complejo sistema de múltiples estratos que hay en Japón. Los canales de distribución que existen en los países en desarrollo se deben a que sus economías dependen ostensiblemente de bienes manufacturados importados. En una estructura de distribución tradicional, orientada a las importaciones, un importador controla una oferta fija de bienes, y el sistema de marketing se desarrolla en torno a la filosofía de que venderá esa oferta limitada de bienes a precios elevados a un número pequeño de clientes ricos. En el mercado de vendedores resultante, no es necesario que haya penetración de mercado ni distribución masiva porque la demanda excede la oferta y, en la mayoría de los casos, el cliente buscará la oferta que está en manos de un número limitado de intermediarios. Esta configuración afecta el desarrollo de los intermediarios y sus funciones. La dimensión de los sistemas de distribución es local, en lugar de nacional, y la relación entre el importador y el intermediario en los mercados es considerablemente diferente de la que se presenta en un sistema de marketing masivo. La idea de que el canal es una cadena de intermediarios que desempeñan actividades específicas, donde cada uno de ellos vende el producto a una unidad más pequeña que está después de él, hasta que la cadena llega al consumidor final, no es común en un sistema orientado a las importaciones. Dado que el importador-mayorista suele desempeñar la mayor parte de las funciones del marketing, en ese sistema no existen, o no están desarrolladas, las entidades independientes que cumplen las funciones de publicidad, investigaciones de mercado, depósito y almacén, transporte, financiamiento y otras más que encontramos en una infraestructura de marketing madura y desarrollada. Por lo tanto, existen pocas entidades independientes que apoyen el desarrollo de un sistema de distribución enteramente integrado. Compare esta situación con la filosofía de distribución del consumo masivo que prevalece en Estados Unidos y en otros países industrializados. En esos mercados, un proveedor no domina la oferta, la oferta puede aumentar o disminuir dentro de un cierto rango, y la maximización de las ganancias se presenta en el punto de la capacidad de producción, o cerca del mismo. Por lo general, el mercado es de compradores, y el productor lucha por penetrar el mercado y por empujar los bienes para que lleguen al consumidor, lo cual genera la estructura de un canal muy desarrollado que incluye a una gran variedad de intermediarios, muchos de los cuales ni siquiera son conocidos en los mercados en desarrollo. A medida que China se ha ido desarrollando en el ámbito económico, su sistema de mercado y su estructura de distribución también han ido evolucionando.1 Como hemos dicho, el desarrollo económico es asimétrico y distintas partes de una economía pueden estar en etapas diferentes de desarrollo. Las estructuras de los canales en países que a lo largo de su historia han evolucionado a partir de una base orientada a las importaciones, por lo habitual reflejarán vestigios de sus inicios en un sistema que dista mucho de estar plenamente integrado. En el otro extremo encontramos el sistema japonés de distribución, con sus muchos estratos de intermediarios especializados. Históricamente, en Japón, la distribución ha sido considerada la barrera no arancelaria más efectiva para impedir el ingreso al mercado japonés.2 Sin embargo, ahora el mercado se está abriendo más porque muchos modos tradicionales de operación se están erosionando ante la competencia que presentan compañías extranjeras y porque los consumidores japoneses siguen exigiendo precios más bajos. Sin embargo, éste sigue siendo un magnífico caso de estudio para conocer el efecto general que la cultura tiene en instituciones económicas como los sistemas nacionales de distribución. La estructura japonesa de distribución es tan diferente de su equivalente estadounidense o europea que quienquiera que esté considerando la posibilidad de ingresar a ese mercado la debería estudiar con detenimiento. El sistema japonés presenta cuatro características distintivas: 1) una estructura dominada por muchos intermediarios pequeños que tienen tratos con muchos minoristas pequeños; 2) el control del canal en manos de los fabricantes; 3) una filosofía de negocios configurada por una cultura única, y 4) leyes que protegen la base del sistema: el pequeño minorista. La densidad de intermediarios, minoristas y mayoristas que componen el mercado japonés no tiene paralelo en ningún país industrializado de Occidente. La estructura japonesa tradicional sirve a consumidores que efectúan compras pequeñas y frecuentes en tiendas pequeñas ubicadas convenientemente. Una densidad igual de mayoristas apoya a la gran densidad de tiendas pequeñas con inventarios pequeños. No es raro que los bienes de consumo pasen por tres o cuatro intermediarios antes de llegar al consumidor; es decir, del productor al mayorista primario, al secundario, al regional y al local y, entonces, por último, del minorista al consumidor.

Si bien otros países tienen números considerables de pequeñas tiendas minoristas, la principal diferencia entre las tiendas pequeñas (nueve empleados o menos) de Japón y las de Estados Unidos es el porcentaje del total de las ventas al detalle que representan los pequeños minoristas. En Japón, las tiendas pequeñas representan 59.1% de las ventas de alimentos al detalle; en Estados Unidos, las tiendas pequeñas generan 35.7% de las ventas de alimentos. Los datos más llamativos de la ilustración 15.1 serían las reducciones del gasto en distintas clases de tiendas en Japón. El único crecimiento registrado en los pasados cinco años es en la categoría de productos para la salud y la belleza. Por supuesto, los japoneses gastan menos en tiendas para el hogar y para el jardín porque tienen menos metros cuadrados que sus homólogos estadounidenses o alemanes. Japón también es famoso por la enorme cantidad de máquinas vendedoras, como bien reflejan estos datos. En esos tres países, el crecimiento más pronunciado del gasto corresponde a las compras por internet. Como veremos en una sección posterior, las ventas al detalle en Japón están sufriendo cambios profundos. Si bien todavía es correcto describir al mercado japonés como uno con gran densidad de intermediarios, el número de tiendas está disminuyendo a medida que son remplazadas por tiendas de descuento y especializadas más grandes. El número de tiendas minoristas disminuyó más de 13% entre 2004 y 2009, y el número de tiendas minoristas con cuatro empleados o menos bajó más de 15%. Estas tiendas pequeñas cumplen una función muy importante para los consumidores japoneses. La elevada densidad de la población, la tradición de los viajes frecuentes a la tienda, el énfasis en el servicio, la frescura y la calidad, y los mayoristas que proporcionan apoyo financiero, entregas frecuentes de lotes pequeños y otros beneficios más, se combinan para apoyar el elevado número de tiendas pequeñas. Los fabricantes dependen de los mayoristas para que presten infinidad de servicios a otros miembros de la red de distribución. El mayorista proporciona servicios de financiamiento, distribución física, almacenaje, inventario, promoción y cobranza a otros miembros del canal. El sistema funciona porque los mayoristas y todos los demás intermediarios canal abajo están ligados a los fabricantes por una serie de prácticas e incentivos que tienen por objeto asegurar un apoyo sólido para el marketing de sus productos y para sacar a los competidores rivales del canal. Los mayoristas suelen actuar como intermediarios agentes y extienden el control del fabricante a lo largo del canal hasta el nivel de los minoristas. Los estrechos vínculos económicos, la dependencia que generan las costumbres comerciales y la larga estructura de los canales japoneses de distribución van de la mano con la filosofía de negocios orientada a las relaciones que hace hincapié en la lealtad, la armonía y la amistad. El sistema de valores apoya las relaciones duraderas entre el distribuidor y el proveedor que difícilmente cambiarán mientras cada una de las partes perciba que ofrecen una ventaja económica. El socio tradicional, el que está adentro, suele gozar de esa ventaja. La ausencia general de la competencia de precios, la prestación de servicios costosos y otras ineficiencias provocan que el costo de los bienes de consumo japoneses sea uno de los más elevados del mundo. De hecho, basta con comparar las pagas al tipo de cambio corriente (es decir, el PIB per cápita); los japoneses ganan 42 832 dólares frente a los 47 199 de los estadounidenses.

Sin embargo, tomando en cuenta lo que se puede comprar con esas pagas (es decir, el PIB per cápita a paridad de precio de compra [PPC]), la ventaja estadounidense aumenta porque los bienes cuestan más en Japón y porque el poder adquisitivo de los nipones apenas equivale a 33 753 dólares. 3 Estos precios crean el clima perfecto para los descuentos, que están empezando a ser un factor medular. El consumidor japonés contribuye a que no desaparezca la esencia tradicional del sistema de distribución con sus viajes frecuentes a la tienda, sus compras pequeñas, porque prefiere el servicio personal en lugar del precio y porque tiende a ser leal a marcas que percibe como de gran calidad. Además, las leyes japonesas colocan al pequeño minorista en una posición de enorme ventaja frente al desarrollo de tiendas más grandes y la competencia. Todos estos factores han apoyado la viabilidad de las tiendas pequeñas y del sistema establecido para que no desaparezcan, pero el cambio de actitudes de muchos consumidores está empezando a debilitar las riendas que los minoristas tradicionales tienen en el mercado. La competencia que proviene de las tiendas minoristas grandes había estado controlada casi enteramente por la Daitenho, o la Ley de las tiendas minoristas de gran escala (y sus encarnaciones más recientes). Esta ley, elaborada para proteger a los pequeños minoristas contra la intrusión de los grandes a sus mercados, requería que toda tienda con más de 5 382 pies cuadrados (500 metros cuadrados) debía contar con autorización del gobierno de la prefectura para “construirse, expandirse, permanecer abierta más horas durante la noche o cambiar los días del mes en los que debía permanecer cerrada”. Todas las propuestas para tiendas nuevas “grandes” primero eran calificadas por el Ministerio de Industria y Comercio Internacional (MICI). Luego, si los minoristas locales aceptaban el plan de forma unánime, éste se aprobaba sin tardanza. Sin embargo, sin la autorización de la prefectura, el plan era regresado para aclaraciones y modificaciones, proceso que podía tardar varios años (10 años no era un plazo insólito) para su aprobación. La Iniciativa de Impedimentos Estructurales del gobierno de Estados Unidos, la desregulación y, en fecha más reciente, Walmart han provocado que las prácticas japonesas de distribución cambien. Sin embargo, al final de cuentas, sólo los distribuidores locales que se opongan a los métodos tradicionales, proporcionando a los consumidores productos de calidad a precios competitivos justos, podrán provocar la desaparición del sistema tradicional de distribución. Las tiendas de descuento especializadas están brotando por doquier y los emprendedores están bajando enormemente los precios mediante las compras directas y evitando del todo el sistema de distribución. Por ejemplo, Kojima, una tienda de descuento de aparatos electrónicos de consumo, practica lo que llama “compras globales” y adquiere mercancía en cualquier lugar del mundo a precio tan barato como sea posible. El nexo de Kojima con General Electric le permite vender un refrigerador GE de 410 litros por 640 dólares, precio muy inferior al normal de 1 925, y bajar el modelo de 550 litros de 3 462 dólares a 1 585 dólares. Hoy en día, pocos son los países que están lo bastante aislados como para que los cambios económicos y políticos globales no los afecten. Estas corrientes de cambio están alterando todos los niveles del tejido económico, inclusive la estructura de la distribución.4 Las estructuras tradicionales de los canales siguen presentes en muchos lugares; Nestlé presume de su distribución “a pie, en bicicleta y en taxi” en África,5 y Muhtar Kent, el CEO de Coca-Cola promete: “Llegamos a todos los lugares de África. Llegamos a toda ciudad, todo pueblo y toda aldea”.6 Pero estas estructuras de los canales también están dando lugar a otras formas, otras alianzas y otros procesos; algunas menos rápido que otras, pero todas ellas están cambiando.7 Por ejemplo, Walmart, Tesco y Carrefour tienen problemas con sus tiendas más grandes y, en consecuencia, las están achicando para que sean “hipermercados compactos” de entre tres y cinco mil metros cuadrados, en lugar de los 10 mil actuales.8 Piense en el éxito que eBay ha tenido recientemente en China9 y en el brote de compras por internet registrado en Japón después del terremoto/tsunami.10 Las presiones para están siempre buscando el camino para llegar de manera rentable a segmentos del mercado que por el momento están cubiertos por sistemas tradicionales costosos de distribución. En India, el conocido amontonamiento de los minoristas tradicionales está cediendo el paso a los anchos pasillos de los nuevos supermercados, nacionales y extranjeros. En Reino Unido, Tesco está instalando bancos al público en sus tiendas,11 y Anthropologie también está sondeando las aguas en ese terreno.12 A medida que las utilidades de Carrefour caen en Europa, la compañía está importando nuevos conceptos de sus hipermercados en Brasil, como un número más pequeño de unidades en inventario (SKU, siglas de stock keeping units).13 Ahora se están introduciendo métodos como el marketing directo, las ventas de puerta en puerta, los hipermercados, los establecimientos de descuento, los centros comerciales, las ventas por catálogo, internet y otros métodos de distribución en un intento por ofrecer canales eficientes de distribución. Los importadores y los minoristas también están participando más en el desarrollo de nuevos productos;14 por ejemplo, el enorme Grupo Elektra, la compañía mexicana del ramo de los aparatos electrónicos y los electrodomésticos, ha formado una alianza con Automobile Works Group de Beijing para desarrollar y fabricar autos de precio muy bajo para el mercado de México y para exportarlos. Con el tiempo, algunas de las tendencias importantes de la distribución llevarán a que los intermediarios de diferentes países tengan más cosas en común y menos diferencias. Por ejemplo, Walmart se está expandiendo por todo el mundo; de México a Brasil y de Europa a Asia. La única gran decepción del coloso estadounidense ha sido la falta de escala y utilidades en Corea del Sur; en 2006, la compañía vendió las cinco tiendas que tenía en ese país.15 Avon se está expandiendo en Europa del Este, Amway en China y L.L. Bean y Lands’ End han ingresado con mucho éxito en el mercado japonés. El efecto de todas estas intrusiones en los sistemas tradicionales de distribución es el cambio que está provocando que los conceptos de los descuentos, el marketing directo, el autoservicio, los supermercados, la venta de grandes volúmenes y el e-commerce sean comunes en todo el mundo, elevando el clima de la competencia a un nivel hasta ahora desconocido. A medida que los minoristas estadounidenses han invadido Europa, los formales minoristas a nivel nacional se han ido fusionando con ex competidores y con compañías de otros países para formar empresas para toda Europa. Carrefour, una compañía francesa global, se fusionó con Promodes, una de sus feroces competidoras, también francesa, para crear, según dijo su CEO, “un líder minorista mundial”. Sainsbury, el gigante de los supermercados de Reino Unido, ha formado una alianza con Esselunga de Italia (supermercados), Docks de Francia (hipermercados, supermercados y tiendas de descuento) y Delhaize de Bélgica (supermercados). La alianza de las cuatro compañías representa la oportunidad de que conjunten su experiencia y su poder de compra para afrontar mejor la creciente competencia y la oportunidad que ofrecen el mercado europeo único y el euro. Mientras que los minoristas europeos consideran que una Europa unificada es una oportunidad para la expansión paneuropea, los minoristas extranjeros se sienten atraídos por los elevados márgenes y los precios. Costco, el minorista estadounidense que se extiende en grandes naves, consideró que los elevados márgenes brutos que existen en los supermercados británicos (7 a 8% en comparación con 2.5 a 3% en Estados Unidos) eran una oportunidad. Al principio, los precios de Costco serán entre 10 y 20% más bajos que los de los minoristas locales rivales. En toda Europa se está registrando la expansión fuera del país propio y se están presentando nuevas clases de ventas al detalle. El Corte Inglés, la cadena de tiendas de departamentos más grande de España, no sólo está ingresando a Portugal y otros países europeos, sino que también fue uno de los primeros minoristas en ofrecer en España un supermercado virtual por internet (www.corteingles.es) y en patrocinar dos canales de compras desde casa, que se transmiten las 24 horas del día. Cada vez es más frecuente que los minoristas pequeños también se expandan a ultramar. Mango, otro minorista español, abrió una tienda en la ciudad de Nueva York y, al igual que otros competidores europeos, estaba aprovechando los bajos costos de operación que existían en Estados Unidos en ese momento debido a la baja del dólar. Una de las fortalezas de Walmart es su sistema interno basado en internet, que permite que sus transacciones con los proveedores sean sumamente eficientes y disminuyan sus costos de operación. De hecho, está comprando a minoristas en problemas en todo el mundo con la intención de “salvarlos” con sus tecnologías de distribución. Este mismo tipo de sistema está disponible en internet para las transacciones de empresa-a-empresa y de empresa-a-consumidor. Por ejemplo, General Motors, Ford Motor Company y Daimler Chrysler han creado un sitio en línea llamado Covisint (www.covisint.com) para comprar partes de automóviles a los proveedores, y se espera que el sitio ahorre a las compañías muchos millones de dólares. Una orden de compra típica le cuesta a Ford 150 dólares, mientras que un pedido en tiempo real vía Covisint le costará alrededor de 15 dólares. Sears Roebuck y Carrefour de Francia han creado GlobalNetXchange (www. gnx.com), una bolsa minorista que permite a los minoristas y a sus proveedores realizar transacciones en línea. Cualquier compañía que tenga un navegador web puede acceder a la bolsa para comprar, vender, intercambiar o subastar bienes y servicios. Se espera que la bolsa, descrita como “uno de los cambios más drásticos en la distribución de consumos de producto en una década”, baje los costos para el comprador y para el proveedor. Si se desarrollan más bolsas así, sólo cabe especular cuál será su efecto para los intermediarios tradicionales de los canales. Ya hemos visto las repercusiones que los minoristas del e-commerce, como Amazon.com, Dell Computer, eBay y otros que se están expandiendo globalmente, han tenido en las ventas al detalle tradicionales en años recientes. La mayoría de los minoristas con tiendas de cemento están experimentando o cuentan con sitios web totalmente desarrollados, y algunos de ellos son simples extensiones de sus tiendas normales, lo cual les permite extender su alcance a todo el mundo. Algunos ejemplos son L. L. Bean, Eddie Bauer y Lands’ End. Uno de los aspectos más complicados de las ventas por web es la entrega de los bienes. Una de las características distintivas del programa 7dream de las tiendas 7-Eleven de Japón es el uso de las tiendas de conveniencia como puntos para recoger pedidos de mercancía vendida por web. El programa ha funcionado tan bien en Japón, que Ito-Yokado Corporation, dueña de 7-Eleven de Japón y de 72% de la cadena estadounidense, está exportando la idea a las tiendas de Estados Unidos. En la zona de Dallas-Fort Worth, 250 tiendas han instalado una suerte de cajeros automáticos ligados a un sistema de entregas y pagos que promete hacer de las tiendas 7-Eleven un depósito para el e-commerce. FedEx, UPS y otros servicios de paquetería que han sido la columna vertebral de las entregas del e-commerce en Estados Unidos ahora están ofreciendo servicios similares para clientes extranjeros de compañías estadounidenses dedicadas al e-commerce, así como para otras con sede en el exterior. Cuando los bienes trascienden fronteras, UPS y otras compañías ofrecen entregas completas, inclusive los trámites de aduanas y los servicios de agentes aduanales. La mayor parte de esas compañías de servicios están establecidas en Europa y Japón y están creando redes en Latinoamérica y China. Las repercusiones de estas tendencias y otras más cambiarán los sistemas tradicionales de la distribución y el marketing. Mientras esta reciente revolución en las ventas al detalle sigue fluyendo, se irán inventando nuevos sistemas de ventas al detalle y de intermediarios, y las compañías establecidas los experimentarán, tratando de encontrar caminos para mantener su ventaja competitiva. Es más, cada vez resulta más peligroso pensar en los competidores en términos de compañías individuales; en los negocios internacionales en general y en los sistemas de distribución en particular, cada vez es más necesario adoptar una perspectiva de redes. Es decir, las compañías deben entenderse en el contexto de las redes comerciales de las que forman parte.16 Estos cambios resonarán en toda la cadena de distribución antes de que se establezcan conceptos nuevos y de que los sistemas se estabilicen. Desde la revolución que se registró en la distribución en Estados Unidos después de la Segunda Guerra Mundial, que al final de cuentas condujo al establecimiento minorista de gran tamaño, no había existido tal potencial de cambio en los sistemas de distribución. Sin embargo, este cambio no estará limitado en su mayor parte a Estados Unidos, sino que será mundial.

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Managing Control Forces.

Managing Control Forces. As airplanes evolved from stick and wire contraptions to awesome supersonic machines, the pilot at the center of it all has not changed. Desirable maximum and minimum levels of pilot stick, yoke, and rudder pedal control forces required to steer and maneuver are much the same, but the engineering solutions that bring these forces about have changed with the times. Desirable Control Force Levels. In 1936 and 1937, NACA research pilots and engineers Melvin N. Gough, A. P. Beard, and William H. McAvoy used an instrumented cockpit to establish maximum force levels for control sticks and wheels. In lateral control the maximums for one hand are 30 pounds applied at a stick grip and 80 pounds applied at the rim of a control wheel. In longitudinal control the maximums are 35 pounds for a stick and 50 pounds for a wheel. Lower forces are desirable and easily attainable with modern artificial feel systems. The Federal Aviation Administration allows higher forces for transport-category airplanes under FAR Part 25. Seventy-five pounds is allowed for temporary application. However, the data compilation for the handbook accompanying MIL-STD-1797, a current military document, shows that a little over 50 percent of male pilots and fewer than 5 percent of female pilots are capable of this force level. Gough-Beard-McAvoy force levels are generally used as maximum limits for conventional stick, yoke, and rudder pedal controllers, but much lower control force levels are specified for artificial-feel systems and for side-stick controls operated by wrist and forearm motions. Background to Aerodynamically Balanced Control Surfaces. When airplanes and their control surfaces became large and airplane speeds rose to several hundred miles per hour, control forces grew to the point where even the Gough Beard-McAvoy force limits were exceeded. Pilots needed assistance to move control surfaces to their full travels against the pressure of the air moving past the surfaces. An obvious expedient was to use those same pressures on extensions of the control surface forward of the hinges, to balance the pressure forces that tried to keep the control surfaces faired with the wing. The actual developmental history of aerodynamically balanced control surfaces did not proceed in a logical manner. But a logical first step would have been to establish a background for design of the balances by developing design charts for the forces and hinge moments for unbalanced control surfaces. That step took place first in Great Britain. Glauert’s calculations were based on thin airfoil theory. W. G. Perrin followed in the next year with the theoretical basis for control tab design. The next significant step in the background for forces and hinge moments for unbalanced control surfaces was NACA pressure distribution tests on a NACA 0009 airfoil, an airfoil particularly suited to tail surfaces. The trends with control surface hinge position along the airfoil chord match Glauert’s thin airfoil theory exactly, but with lower flap effectiveness and hinge moment than the theoretical values. Ames and his associates developed a fairly complex scheme to derive three-dimensional wing and tail surface data from the two-dimensional design charts. That NACA work was complemented for horizontal tails by a collection of actual horizontal tail data for 17 tail surfaces, 8 Russian and 3 each Polish, British, and U.S. Full control surface design charts came later, with the publication of stability and control handbooks in several countries. Horn Balances. The first aerodynamic balances to have been used were horn balances, in which area ahead of the hinge line is used only at the control surface tips. In fact, rudder horn balances appear in photos of the Moisant and Bleriot XI monoplanes of the year 1910. It is doubtful that the Moisant and Bl´eriot horn balances were meant to reduce control forces on those tiny, slow airplanes. However, the rudder and aileron horn balances of the large Curtiss F-5L flying boat of 1918 almost certainly had that purpose. Wind-tunnel measurements of the hinge moment reductions provided by horn balances show an interesting characteristic. Control surface hinge moments arise from two sources: control deflection with respect to the fixed surface and angle of attack of the fixed or main surface. The relationship is given in linearized dimensionless form by the equation hinge moment coefficient equals to the derivative of the hinge moment coefficient with respect to the control surface deflection times control surface deflection with respect to the fixed surface plus the derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface times the angle of attack of the fixed or main surface, where the hinge moment coefficient is the hinge moment divided by the surface area and mean chord aft of the hinge line and by the dynamic pressure. Both derivatives are normally negative in sign. A negative derivative of the hinge moment coefficient with respect to the control surface deflection means that when deflected the control tends to return to the faired position. A negative derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface means that when the fixed surface takes a positive angle of attack the control floats upward, or trailing edge high. Upfloating control surfaces reduce the stabilizing effect of the tail surfaces. It was discovered that horn balances produce positive changes in the derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface, reducing the up floating tendency and increasing stability with the pilot’s controls free and the control surfaces free to float. This horn balance advantage has to be weighed against two disadvantages. The aerodynamic balancing moments applied at control surface tips twist the control surface. Likewise, flutter balance weights placed at the tips of the horn, where they have a good moment arm with respect to the hinge line, lose effectiveness with control surface twist. A horn balance variation is the shielded horn balance, in which the horn leading edge is set behind the fixed structure of a wing or tail surface. Shielded horn balances are thought to be less susceptible to accumulating leading-edge ice. Shielded horn balances are also thought to be less susceptible to snagging a pilot’s parachute lines during bailout. Overhang or Leading-Edge Balances. When control surface area ahead of the hinge line is distributed along the span of the control surface, instead of in a horn at the tip, the balance is called an overhang or a leading-edge balance. Overhang design parameters are the percentage of area ahead of the hinge line relative to the total control surface area and the cross-sectional shape of the overhang. Experimental data on the effects of overhang balances on hinge moments and control effectiveness started to be collected as far back as the late 1920s. Some of these early data are given by Abe Silverstein and S. Katzoff. Airplane manufacturers made their own correlations of the effects of overhang balances, notably at the Douglas Aircraft Company. As in many other disciplines, the pressure of World War II accelerated these developments. Root and his group at Douglas found optimized overhang balance proportions for the SBD-1 Dauntless dive bomber by providing for adjustments on hinge line location and overhang nose shape on the SBD-1 prototype, known as the XBT-2. Root wrote a NACA Advance Confidential Report in May 1942 to document a long series of control surface and other modifications leading to flying qualities that satisfied Navy test pilots. For example, in 1 of 12 horizontal tail modifications that were flight tested, the elevator overhang was changed from an elliptical to a “radial,” or more blunt, cross-section, to provide more aerodynamic balancing for small elevator movements. This was to reduce control forces at high airspeeds. Overhang aerodynamic balance, in combination with spring tabs, continue in use in Douglas transport airplanes, from the DC-6 and DC-7 series right up to the elevators and ailerons of the jet-powered DC-8. The DC-8’s elevator is balanced by a 35-percent elliptical nose overhang balance. Remarkably constant hinge moment coefficient variations with elevator deflection are obtained up to a Mach number of 0.96. George S. Schairer came to the Boeing Company with an extensive control surface development background at Convair and in the Cal Tech GALCIT 10-foot wind tunnel. Although early B-17s had used spring tabs, Schairer decided to switch to leading-edge balances for the B-17E and the B-29 bombers. The rounded nose overhang balances on the B-29s worked generally well, except for an elevator overbalance tendency at large deflection angles. Large elevator angles were used in push-overs into dives for evasive action. William Cook remarks, “A World War II B-29 pilot friend of mine was quite familiar with this characteristic, so the fact that he got back meant this must have been tolerable.” However, overhang balance was not effective for the B-29 ailerons. Forces were excessive. The wartime and other work on overhang aerodynamic balance was summarized by the NACA Langley Research Department. The Toll report remains a useful reference for modern stability and control designers working with overhang aerodynamic balances and other aerodynamic balance types as well. Frise Ailerons. The hinge line of the Frise aileron, invented by Leslie George Frise, is always at or below the wing’s lower surface. If one sees aileron hinge brackets below the wing, chances are that one is looking at a Frise aileron. Frise ailerons were used on many historic airplanes after the First World War, including the Boeing XB-15 and B-17, the Bell P-39, the Grumman F6F-3 and TBF, and the famous World War II opponents – the Spitfire, Hurricane, and Focke-Wulf 190 fighters. Frise ailerons were applied to both the Curtiss-Wright C-46 Commando and the Douglas C-54 Sky master during World War II, to replace the hydraulic boost systems used in their respective prototypes. With the hinge point below the wing surface, an arc drawn from the hinge point to be tangent to the wing upper surface penetrates the wing lower surface some distance ahead of the hinge line, thus establishing an overhang balance. The gap between the aileron and wing can be made as narrow as desired by describing another arc slightly larger than the first. This in fact is typical of the Frise aileron design. The narrow wing-to-aileron gap reduces air flow from the high-pressure wing under surface to the lower pressure wing upper surface, reducing drag. The Frise aileron is less prone to accumulate ice for that same reason. It was promoted by the U.S. Army Air Corps Handbook for Airplane Designers as an anti-icing aileron. The relatively sharp Frise aileron nose develops high velocities and low static pressures when projecting below the wing lower surface, when the aileron goes trailing-edge up. This generally overbalances the up-going aileron. On the other hand, the overbalanced-up aileron is connected by control cables or pushrods to the down-going aileron on the other side of the wing. The sharp Frise nose on that side is within the wing contour; the down aileron is underbalanced. By connecting the up and down sides through the pilot’s controls the combination is made stable, with lowered control forces relative to ailerons without aerodynamic balance. The sharp nose of the Frise aileron, protruding below the wing’s lower surface for trailing edge-up deflections, has been thought to help reduce adverse yaw when rolling. The trailing edge-up aileron is on the down-going wing in a roll. In adverse yaw, the down-going wing moves forward, while the airplane yaws in a direction opposite to that corresponding to a coordinated turn. Flow separation from the Frise aileron sharp nose is supposed to increase drag on the down-going wing, pulling it back and reducing adverse yaw. This happens to some extent, but for normal wing plan forms with aspect ratios above about 6, adverse yaw is actually dominated by the aerodynamic yawing moment due to rolling, and is little affected by Frise ailerons. Adverse yaw must be overcome by good directional stability complemented by rudder deflection in harmony with aileron deflection. A Frise aileron design used on the Douglas SBD-1 Dauntless. This design was the seventh and final configuration tested in 1939 and 1940. Nose shape, wing-to-aileron gap, hinge line position, and gap seal parameters were all varied. Flight test evidence of Frise aileron oscillations on a Waco XCG-3 glider due to alternate stalling and unstalling of the sharp nose at extreme up-aileron travels. The upper photo shows the bulky roll rate recorder. The lower photo is a rate of roll trace for two abrupt full aileron rolls. Aileron oscillations are shown by the ripples at the peak roll rate values. Frise ailerons turned out to have problems on large airplanes, where there is a long cable run from the control yoke to the ailerons. In the development of the Waco XCG-3 glider in 1942, the sharp nose of its Frise ailerons alternately stalled and unstalled when the ailerons were held in a deflected position. This created severe buffeting. The aileron nose stalled at the largest angle, reducing the balancing hinge moment. Control cable stretch allowed the aileron to start back toward neutral. But as the aileron angle reduced the nose unstalled, the aerodynamic balance returned, and the aileron started back toward full deflection, completing the cycle. The fix for the XCG-3 was to limit up-aileron angles from 30 to 20 degrees and to round off the sharp nose to delay stalling of the nose. Modified Frise ailerons, with noses raised to delay stalling, had been tested in Britain by A. S. Hartshorn and F. B. Bradfield as early as 1934. The advantages of raised-nose Frise ailerons were verified in NACA tests on a Curtiss P-40. Beveled trailing edges were added to the raised-nose Frise ailerons on the P-40, to make up for loss in aerodynamic balance at small deflections. Lateral stick force remained fairly linear and very low up to a total aileron deflection of 48 degrees, giving a remarkably high dimensionless roll rate of 0.138 at 200 miles per hour. Aileron Differential. The larger travel of one aileron relative to the other is called aileron differential. Aileron differential is a method of reducing control forces by taking advantage of hinge moment bias in one direction. At positive wing angles of attack, the hinge moment acting on both ailerons is normally trailing-edge up, and we say the ailerons want to float up. Assume that the up-going aileron is given a larger travel than the down-going aileron for a given control stick or wheel throw. Then, the work done by the trailing-edge-up hinge moment acting on the up-going aileron can be nearly as great as the work the pilot does in moving the down-going aileron against its up-acting hinge moment, and little pilot force is needed to move the combination. The differential appropriate for up-float is more trailing-edge-up angle than down. Typical values are 30 degrees up and 15 degrees down. The floating hinge moment can be augmented, or even reversed, by fixed tabs. Aileron up-float, associated with negative values of the hinge moment derivative, is greatest at high wing angles of attack. Neglecting accelerated flight, high wing angles of attack occur at low airspeeds. Thus, aileron differential has the unfortunate effect of reducing aileron control forces at low airspeeds more than at high airspeeds, where reductions are really needed. In addition to the force-lightening characteristic of aileron differential, increased up relative to down aileron tends to minimize adverse yaw in aileron rolls, which is the tendency of the nose to swing initially in the opposite direction to the commanded roll. Adverse yaw in aileron rolls remains a problem for modern airplanes, especially those with low directional stability, such as tailless airplanes. Where stability augmentation is available, it is a more powerful means of overcoming adverse yaw than aileron differential. Balancing or Geared Tabs. Control surface tabs affect the pressure distribution at the rear of control surfaces, where there is a large moment arm about the hinge line. A trailing-edge-up tab creates relative positive pressure on the control’s upper surface and a relative negative pressure peak over the tab-surface hinge line. Both pressure changes drive the control surface in the opposite direction to the tab, or trailing-edge-down. When a tab is linked to the main wing so as to drive the tab in opposition to control surface motion, it is called a balancing or geared tab. Balancing tabs are used widely to reduce control forces due to control surface deflection. They have no effect on the hinge moments due to wing or tail surface angle of attack. Airplanes with balancing tabs include the Lockheed Jet star rudder, the Bell P-39 ailerons, and the Convair 880M. Trailing-Edge Angle and Beveled Controls. The included angle of upper and lower surfaces at the trailing edge, or trailing edge angle, has a major effect on control surface aerodynamic hinge moment. This was not realized by practicing stability and control engineers until well into the World War II era. For example, a large trailing-edge angle is now known to be responsible for a puzzling rudder snaking oscillation experienced in 1937 with the Douglas DC-2 airplane. Quoting from an internal Douglas Company document of July 12, 1937, by L. Eugene Root: The first DC-2s had a very undesirable characteristic in that, even in smooth air, they would develop a directional oscillation. In rough air this characteristic was worse, and air sickness was a common complaint.... It was noticed, by watching the rudder in flight, that during the hunting the rudder moved back and forth keeping time with the oscillations of the airplane. It is common knowledge that the control surfaces were laid out along airfoil lines. Because of this fact, the rearward portion of the vertical surface, or the rudder, had curved sides. It was thought that these curved sides were causing the trouble because of separation of the air from the surface of the rudder before reaching the trailing edge. In other words, there was a region in which the rudder could move and not hit “solid” air, thus causing the movement from side to side. The curvature was increased towards the trailing edge of the rudder in such a way as to reduce the supposedly “dead” area.... The change that we made to the rudder was definitely in the wrong direction, for the airplane oscillated severely.... After trying several combinations on both elevators and rudder, we finally tried a rudder with straight sides instead of those which would normally result from the use of airfoil sections for the vertical surfaces. We were relieved when the oscillations disappeared entirely upon the use of this type of rudder. The Douglas group had stumbled on the solution to the oscillation or snaking problem, reduction of the rudder floating tendency through reduction of the trailing-edge angle. Flat sided control surfaces have reduced trailing-edge angles compared with control surfaces that fill out the airfoil contour. We now understand the role of the control surface trailing edge angle on hinge moments. The wing’s boundary layer is thinned on the control surface’s windward side, or the wing surface from which the control protrudes. Conversely, the wing’s boundary layer thickens on the control surface’s leeward side, where the control surface has moved away from the flow. Otherwise stated, for small downward control surface angles or positive wing angles of attack the wing’s boundary layer is thinned on the control surface bottom and thickened on the control’s upper surface. The effect of this differential boundary layer action for down-control angles or positive wing angles of attack is to cause the flow to adhere more closely to the lower control surface side than to the upper side. In following the lower surface contour the flow curves toward the trailing edge. This curve creates local suction, just as an upward-deflected tab would do. On the other hand, the relatively thickened upper surface boundary layer causes the flow to ignore the upper surface curvature. The absence of a flow curve around the upper surface completes the analogy to the effect of an upward-deflected tab. The technical jargon for this effect is that large control surface trailing-edge angles create positive values of the derivative of the hinge moment coefficient with respect to the control surface deflection and the derivative of the hinge moment coefficient with respect to angle of attack of the fixed or main surface, which are , the floating and restoring derivatives, respectively. The dynamic mechanism for unstable lateral-directional oscillations with a free rudder became known on both sides of the Atlantic a little after the Douglas DC-2 experience. Unstable yaw oscillations were calculated in Britain for a rudder that floated into the wind. This was confirmed in two NACA studies. The aerodynamic connection between trailing-edge angle and control surface hinge moment, including the floating tendency, completed the story. Following the success of the flat-sided rudder in correcting yaw snaking oscillations on the Douglas DC-2, flat-sided control surfaces became standard design practice on Douglas airplanes. William H. Cook credits George S. Schairer with introducing flat-sided control surfaces at Boeing, where they were used first on the B-17E and B-29 airplanes. Trailing edge angles of fabric-covered control surfaces vary in flight with the pressure differential across the fabric. A Douglas C-74 transport was lost in 1946 when elevator fabric bulging between ribs increased the trailing-edge angle, causing pitch oscillations that broke off the wing tips. C-74 elevators were metal-covered after that. Understanding of the role of the trailing-edge angle in aerodynamic hinge moments opened the way for its use as another method of control force management. Beveled control surfaces, in which the trailing-edge angle is made arbitrarily large, is such an application. Beveled control surfaces, a British invention of World War II vintage, work like balancing tabs for small control surface angles. The beveled-edge control works quite well for moderate bevel angles. As applied to the North American P-51 Mustang, beveled ailerons almost doubled the available rate of roll at high airspeeds, where high control forces limit the available amount of aileron deflection. But large bevel angles, around 30 degrees, acted too well at high Mach numbers, causing overbalance and unacceptable limit cycle oscillations. Beveled controls have survived into recent times, used for example on the ailerons of the Grumman/Gulfstream AA-5 Tiger and on some Mooney airplanes. Corded Controls. Corded controls, apparently invented in Britain, are thin cylinders, such as actual cord, fastened to control surfaces just ahead of the trailing edge. They are used on one or both sides of a control surface. Corded controls are the inverse of beveled controls. Bevels on the control surface side that projects into the wind produce relative negative pressures near the bevel that balance the control aerodynamically, reducing operating force. On the other hand, cords on the control surface side that projects into the wind create local positive pressures on the surface just ahead of the cord. This increases control operating force. Cords on both sides of a control surface are used to eliminate aerodynamic overbalance. On one side they act as a fixed trim tab. Very light control forces have been achieved by cut and try by starting with aerodynamically overbalanced surfaces, caused by deliberately oversized overhang balances. Quite long cords correct the overbalance, providing stable control forces. In the cut and try process the cords are trimmed back in increments until the forces have been lightened to the pilot’s or designer’s satisfaction. Adjustable projections normal to the trailing edge, called Gurney flaps, act as one-sided cord trim tabs. Spoiler Ailerons. Spoiler ailerons project upward from the upper surface of one wing, reducing lift on that wing and thus producing a rolling moment. Spoiler ailerons are often the same surfaces used symmetrically to reduce lift and increase drag on large jet airplanes for rapid descents and to assist braking on runways. Spoiler ailerons are generally used either to free wing trailing edges for full-span landing flaps or to minimize wing twist due to aileron action on very flexible wings. The aerodynamic details of spoiler operation are still not completely understood, even after years of experiment and theoretical studies. The aerodynamics of a rapidly opened spoiler has two phases, the opening and steady-state phases. Experimental or wind-tunnel studies of rapidly opening upper-wing surface spoilers show a momentary increase in lift, followed by a rapid decrease to a steady-state value that is lower than the initial value. At a wind speed of 39 feet per second, the initial increase is over in less than a half-second, and steady-state conditions appear in about 3 seconds. Results from the computational fluid dynamics method known as the discrete vortex method also predict the momentary increase in lift and associate it with a vortex shed from the spoiler upper edge in a direction that increases net airfoil circulation in the lifting direction. A subsequent shed vortex from the wing trailing edge in the opposite direction reduces circulation to the steady-state value. While suggestive, experimental flow visualization results do not exist that confirm this vortex model. The Yeung, Xu, and Gu experiments show that providing small clearances between the spoiler lower edge and the wing upper surface reduces the momentary increase in lift following spoiler extension. This is consistent with a small shed vortex from the spoiler lower edge of opposite rotation to the vortex shed at the upper edge. A clearance between spoiler and wing surface of this type has also been used to reduce buffet. Separation behind an opened spoiler on a wing upper surface causes distortion of the external or potential flow that is similar to the effect of a flap-type surface with trailing-edge-up deflection. In the latter case, streamlines above the wing are raised toward the wing trailing edge. The effective wing camber is negative in the trailing-edge region, causing a net loss in circulation and lift. The difference in the two cases is that the effective wing trailing edge in the spoiler case is somewhere in the middle of the separated region, instead of at the actual trailing edge, as in the flap-type surface case. The hinge moments of ordinary hinged-flap and slot lip spoiler ailerons are high; brute hydraulic force is used to open them against the airstream. Retractable arc and plug spoiler ailerons are designed for very low hinge moments and operating forces. Although aerodynamic pressures on the curved surfaces of these ailerons are high, the lines of action of these pressures are directed through the hinge line and do not show up as hinge moments. Hinge moments arise only from pressure forces on the ends of the arcs and from small skin friction forces on the curved surfaces. A very early application of plug ailerons was to the Northrop P-61 Black Widow, which went into production in 1943. The P-61 application illustrates the compromises that are needed at times when adapting a device tested in a wind tunnel to an actual airplane. The plug aileron is obviously intended to work only in the up position. However, it turned out not to be possible to have the P-61 plug ailerons come to a dead stop within the wing when retracting them from the up position. The only practical way to gear the P-61 plug ailerons to the cable control system attached to the wheel was by extreme differential. Full up-plug aileron extension on one side results in a slight amount of down-plug aileron angle on the other side. The down-plug aileron actually projects slightly from the bottom surface of the wing. Down-plug aileron angles are shielded from the airstream by a fairing that looks like a bump running span wise. Plug-type spoiler ailerons are subject to nonlinearities in the first part of their travel out of the wing. Negative pressures on the wing’s upper surface tend to suck the plugs out, causing control overbalance. Centering springs may be needed. There can be a small range of reversed aileron effectiveness if the flow remains attached to the wing’s upper surface behind the spoiler for small spoiler projections. Nonlinearities at small deflections in the P-61 plug ailerons were swamped out by small flap-type ailerons, called guide ailerons, at the wing tips. Early flight and wind-tunnel tests of spoilers for lateral control disclosed an important design consideration, related to their chord wise location on the wing. Spoilers located about mid-chord are quite effective in a static sense but have noticeable lags. That is, for a forward-located spoiler, there is no lift or rolling moment change immediately after an abrupt up-spoiler deflection. Since airfoil circulation and lift are fixed by the Kutta trailing edge condition, the lag is probably related to the time required for the flow perturbation at the forward-located spoiler to reach the wing trailing edge. Spoilers at aft locations, where flap-type ailerons are found, have no lag problems. Another spoiler characteristic was found in early tests that would have great significance when aileron reversal became a problem. Spoiler deflections produce far less wing section pitching moment for a given lift change than ordinary flap-type ailerons. The local section pitching moment produced by ailerons twists the wing in a direction to oppose the lift due to the aileron. This is why spoilers are so common as lateral controls on high-aspect ratio wing airplanes. Open slot-lip spoilers on the Boeing 707. Note the exposed upper surface of the first element of the flaps. The open spoilers destroy the slot that ordinarily directs the flow over the flap upper surface, reducing flap effectiveness. The reduced lift improves lateral control power when the spoilers are used asymmetrically or the airplane’s braking power when deployed symmetrically on when the ground. Slot-lip spoiler ailerons are made by hinging the wing structure that forms the upper rear part of the slot on slotted landing flaps. Since a rear wing spar normally is found just ahead of the landing flaps, hinging slot-lip spoilers and installing hydraulic servos to operate them is straightforward. There is a gratifying amplification of slot-lip spoiler effectiveness when landing flaps are lowered. The landing flap slot is opened up when the slot-lip spoiler is deflected up, reducing the flap’s effectiveness on that side only and increasing rolling moment. Internally Balanced Controls. Another control surface balance type that appeared about the same time as beveled controls was the internally balanced control. This control is called the Westland-Irving internal balance in Great Britain. Internally balanced controls are intended to replace the external aerodynamic balance, a source of wing drag because of the break in the wing contour. In the internally balanced control the surface area ahead of the hinge line is a shelf contained completely within the wing contour. Unless the wing is quite thick and has its maximum thickness far aft, mechanical clearance requires either that the shelf be made small, restricting the available amount of aerodynamic balance, or control surface throws be made small, restricting effectiveness. By coincidence, internally balanced controls appeared about the same time as the NACA 65-, 66-, and 67-series airfoil sections. These are the laminar flow airfoils of the 1940s and 1950s. Internally balanced ailerons are natural partners of laminar flow airfoil sections, since aerodynamic balance is obtained without large drag-producing surface cutouts for the overhang. Not only that, but the 66 and 67 series have far aft locations of wing maximum thickness. This helps with the clearance problem of the shelf inside of the wing contour. An internal balance modification that gets around the mechanical clearance problem on thin airfoils is the compound internal balance. The compound shelf is made in two, or even three, hinged sections. The forward edge of the forward shelf section is hinged to fixed airplane structure, such as the tail or wing rear spar. The first application of the compound internal balance appears to have been made by William H. Cook, on the Boeing B-47 Stratojet. Internally balanced elevators and the rudder of the Boeing B-52 have compound shelves on the inner sections of the control surfaces and simple shelves on the outer sections. Compound internal balances continue to be used on Boeing jets, including the 707, 727, and 737 series. The 707 elevator is completely dependent on its internal aerodynamic balance; there is no hydraulic boost. According to Cook, in an early Pan American 707, an inexperienced co-pilot became disoriented over Gander, New found land, and put the airplane into a steep dive. The pilot, Waldo Lynch, had been aft chatting with passengers. He made it back to the cockpit and recovered the airplane, putting permanent set into the wings. In effect, this near-supersonic pullout proved out the 707’s manual elevator control. The 707’s internally balanced ailerons are supplemented by spoilers. The later Boeing 727 used dual hydraulic control on all control surfaces, but internal aerodynamic balance lightens control forces in a manual reversion mode. An electrically driven adjustable stabilizer helps in manual reversion. At least one 727 lost all hydraulic power and made it back using manual reversion. Internally balanced controls were used on a number of airplanes of the 1940s and 1950s. The famous North American P-51 Mustang had internally balanced ailerons, but they were unsealed, relying on small clearances at the front of the shelf to maintain a pressure differential across the shelf. The Curtiss XP-60 and Republic XF-12 both used internally balanced controls, not without operational problems on the part of the XP-60. Water collected on the seal, sometimes turning to ice. Flying or Servo and Linked Tabs. Orville R. Dunn gave 30,000 pounds as a rule-of-thumb upper limit for the weight of transport airplanes using leading-edge aerodynamic balance. Dunn considered that airplanes larger than that would require some form of tab control, or else hydraulically boosted controls. The first really large airplane to rely on tab controls was the Douglas B-19 bomber, which flew first in 1941. The B-19 used pure flying or servo tab control on the rudder and elevator and a plain-linked tab on the ailerons. In a flying tab the pilot’s controls are connected only to the tab itself. The main control surfaces float freely; no portion of the pilot’s efforts go into moving them. A plain-linked tab on the other hand divides the pilot’s efforts in some proportion between the tab and the main surface. The rudder of the Douglas C-54 Sky master transport uses a linked tab. Roger D. Schaufele recalls some anxious moments at the time of the B-19’s first flight out of Clover Field, California. The pilot was Air Corps pilot Stanley Olmstead, an experienced hand with large airplanes. This experience almost led to disaster, as Olmstead “grabbed the yoke and rotated hard” at liftoff, as he had been accustomed to doing on other large airplanes. With the flying tab providing really light elevator forces, the B-19 rotated nose up to an estimated 15 to 18 degrees, in danger of stalling, before Olmstead reacted with forward control motion. Flying tabs are quite effective in allowing large airplanes to be flown by pilot effort alone, although the B-19 actually carried along a backup hydraulic system. A strong disadvantage is the lack of control over the main control surfaces at very low airspeeds, such as in taxi, the early part of takeoffs, and the rollout after landing. The linked tab is not much better in that the pilot gets control over the main surface only after the tab has gone to its stop. Still, by providing control for the B-19, the world’s largest bomber in its time, flying and linked tabs, and the Douglas Aircraft Company engineers who applied them, deserve notice in this history. An apocryphal story about the B-19 flying tab system illustrates the need for a skeptical view of flying tales. MIT’s Otto Koppen was said to have told of a B-19 vertical tail fitted to a B-23 bomber, an airplane the size of a DC-3, to check on the flying tab scheme. The point of the story is that the B-23 flew well with its huge vertical tail. Koppen said this proved that a vertical tail could not be made too large. Unfortunately, this never occurred. Orville Dunn pointed out that the B-23 came years after the B-19, and it didn’t happen. Spring Tabs. Spring tabs overcome the main problem of flying tabs, which do not provide the pilot with control of the main surface at low speeds, as when taxiing. In spring tabs, the pilot’s linkage to the tab is also connected to the main surface through a spring. If the spring is quite stiff, good low-speed surface control results. At the same time, a portion of the pilot’s efforts goes into moving the main surface, increasing controller forces. Spring tabs have the useful feature of decreasing control forces at high airspeeds, where control forces usually are too heavy, more than at low airspeeds. At low airspeeds, the spring that puts pilot effort into moving the main surface is stiff relative to the aerodynamic forces on the surface; the tab hardly deflects. The reverse happens at high airspeeds. At high airspeeds the spring that puts pilot effort into moving the main surface is relatively weak compared with aerodynamic forces. The spring gives under pilot load; the main surface moves little, but the spring gives, deflecting the tab, which moves the main surface without requiring pilot effort. The earliest published references to spring tabs appeared as Royal Air craft Establishment publications. NACA publications followed. But the credit for devising a generalized control tab model that covers all possible variations belongs to Orville R. Dunn. The Dunn model uses three basic parameters to characterize spring tab variations, which include the geared tab, the flying tab, the linked tab, and the geared spring tab. Although the derivation of pilot controller force equations for the different tab systems involve only statics and the virtual work principle, the manipulations required are surprisingly complex. As is typical for engineering papers prepared for publication, Dunn provides only bare outlines of equation derivations. Readers of the 1949 Dunn paper who want to derive his final equations should be prepared for some hard labor. Dunn concluded that spring tabs can produce satisfactory pilot forces on subsonic transport-type airplanes weighing up to several million pounds. At the time of Dunn’s paper, spring tabs had indeed been used successfully on the Hawker Tempest, the Vultee Vengeance rudder, all axes of the Canberra, the rudder and elevator of the Curtiss C-46 Commando, the Republic XF-12, and the very large Convair B-36 bomber. They also would be used later on the Boeing B-52 Stratofortress. Dunn’s account of the DC-6 development tells of rapid, almost overnight, linkage adjustments during flight testing. The major concerns in spring tab applications are careful design and maintenance to minimize control system static friction and looseness in the linkages. The B-19 experience encouraged Douglas engineers to use spring tabs for many years afterwards. Both the large C-124 and C-133 military transports were so equipped. The DC-6, 7, 8, and 9 commercial transports all have some form of spring tab controls, the DC-8 on the elevator and the DC-9 on all main surfaces, right up to the latest MD-90 version. In that case, the switch was made to a powered elevator to avoid increasing horizontal tail size to accommodate the airplane’s stretch. A powered elevator avoids tab losses and effective tail area reductions because tabs move in opposition to elevator travel. The Douglas DC-8 and -9 elevator control tabs are actually linked tabs, in which pilot effort is shared between the tab and the elevator. This gives the pilot control over the elevator when on the ground. The DC-8 and -9 elevator linked tabs are inboard and rather small. The inboard linked tabs are augmented by outboard geared tabs, which increase the flutter margin over single large linked tabs. The DC-9 elevator controls are hybrid in that hydraulic power comes in when the link tab’s deflection exceeds 10 degrees. Spring tabs serve a backup purpose on the fully powered DC-8 ailerons and rudder and on the DC-9 rudder. The tabs are unlocked automatically and used for control when hydraulic system pressure fails. The same tab backup system is used for the Boeing 727 elevator. The spring tab design for the elevators of the Curtiss C-46 Commando was interesting for an ingenious linkage designed by Harold Otto Wendt. Elevator surfaces must be statically balanced about their hinge lines to avoid control surface flutter. Spring tabs should also be statically balanced about their own hinge lines. Spring tab balance weights and the spring mechanisms add to the elevator’s weight unbalance about its hinge line. Wendt’s C-46 spring tab linkage was designed to be largely ahead of the elevator hinge line, minimizing the amount of lead balance required to statically balance the elevator. Spring tabs appear to be almost a lost art in today’s design rooms. Most large airplanes have hydraulic systems for landing gear retraction and other uses, so that hydraulically operated flight controls do not require the introduction of hydraulic subsystems. Furthermore, modern hydraulic control surface actuators are quite reliable. Although spring tab design requires manipulation of only three basic parameters, designing spring tabs for a new airplane entails much more work for the stability and control engineer than specifying parameters for hydraulic controls. Computer-aided design may provide spring tabs with a new future on airplanes that do not really need hydraulically powered controls. Springy Tabs and Down springs. Sometimes called “Vee” tabs, springy tabs first appeared on the Curtiss C-46 Commando twin-engine transport airplane. Their inventor, Roland J.White, used the springy tab to increase the C-46’s allowable aft center of gravity travel. White was a Cal Tech classmate of another noted stability and control figure, the late L. Eugene Root. Springy tabs increase in a stable direction the variation of stick force with airspeed. A springy tab moves in one direction, with the trailing edge upward. It is freely hinged and is pushed from neutral in the trailing-edge-upward direction by a compression spring. An NACA application mounted the springy tab on flexure pivots. The springy tab principle of operation is that large upward tab angles are obtained at low airspeeds, where the aerodynamic moment of the tab about its own hinge line is low compared with the force of the compression spring. Upward tab angle creates trailing-edgedown elevator hinge moment, which must be resisted by the pilot with a pull force. Pull force at low airspeed is required for stick-free stability. The C-46 springy tabs were called Vee tabs because the no-load-up deflection was balanced aerodynamically by the same down rig angle on a trim tab on the opposite elevator. The C-46 springy tabs were also geared in the conventional sense. The compression spring that operated the C-46’s springy tab was a low-rate or long-travel spring with a considerable preload of 52 pounds. Tab deflection occurred only after the preload was exceeded, making the system somewhat nonlinear. Schematic diagram of the elevator trim and vee-tab installations on the Curtiss C-46 Commando. The vee tab augments static longitudinal stick-free stability. Springy tabs were also used successfully on the Lockheed Electra turboprop. Although White is considered the springy tab’s inventor and was the applicant for a patent on the device, it may have been invented independently by the late C. Desmond Pengelly. Springy tabs are not in common use currently because of potential flutter. Irreversible tab drives are preferred to freely hinged tabs from a flutter standpoint. A flutter-conservative means of accomplishing the same effect as a springy tab is the down spring. This is a long-travel spring connected between the elevator linkage and airplane fixed structure. The stick or yoke is pulled forward by the long-travel spring with an essentially constant force. Elevator aerodynamic hinge moment, which would normally fair the elevator to the stabilizer, is low compared with the spring force, and the pilot is obliged to use pull force to hold the elevator at the angle required for trim. As with the springy tab, this provides artificial stick-free stability. Down springs are often found in light airplanes. If the yoke rests against its forward stop with the airplane parked, and a pull force is needed to neutralize yoke travel, either a down spring is installed or, less likely, the elevator has mass unbalance. All-Movable Controls. All-movable tail surfaces became interesting to stability and control designers when high Mach number theory and transonic wind-tunnel tests disclosed poor performance of ordinary flap-type controls. Effectiveness was down, and hinge moments were up. More consistent longitudinal and directional control over the entire speed range seemed possible with all-moving surfaces. However, application of all-moving or slab tail surfaces had to await reliable power controls. One of the first all-moving tail applications was the North American F-100 Super Sabre. According to William E. Cook, a slab horizontal tail was considered for the B-52 and rejected only because of the unreliability of hydraulics at the time. In modern times, there is the Lockheed 1011 transport, with three independent hydraulic systems actuating its all-moving horizontal tail. Of course, modern fighter airplanes, starting with the F-4 in the United States; the Lightning, Scimitar, and Hawk in Britain; and the MiG-21 in Russia, have all-moving horizontal tails. An interesting application is the all-moving tail on a long series of Piper airplanes, beginning with the Comanche PA-24 and continuing with the Cherokee and Arrow series. A geared tab is rigged in the anti-balance sense. The geared tab adds to both control force and surface effectiveness. Fred Weick credits John Thorp with this innovation, inspired by a 1943 report by Robert T. Jones. Mechanical Control System Design Details. Connections between a pilot and the airplane’s control surfaces are in a rapid state of evolution, from mechanical cables or push rods, to electrical wires, and possibly to fiber optics. Push rod mechanical systems have fallen somewhat into disuse; flexible, braided, stainless steel wire cable systems are now almost universal. In an unpublished Boeing Company paper, William H. Cook reviews the mature technology of cable systems: The multi-strand 7×19 flexible steel cables usually have diameters from 1/8 to 3/16 inch. They are not easily damaged by being stepped on or deflected out of position. They are usually sized to reduce stretch, and are much over-strength for a 200-pound pilot force. The swaged end connections, using a pin or bolt and cotter pin, are easily checked. The turnbuckles which set tension are safety-wired, and are easily checked. A Northwest Airlines early Electra crashed due to a turnbuckle in the aileron system that was not secured with safety wire wrap. Since the cable between the cockpit and the control is tensioned, the simplest inspection is to pull it sideways anywhere along its length to check both the tension and the end connections. In a big airplane with several body sections this is good assurance. To avoid connections at each body section joint, the cable can be made in one piece and strung out after joining the sections. The avoidance of fittings required to join cable lengths also avoids the possibility of fittings jamming at bulkheads. Since the cable is rugged, it can be installed in a fairly open manner.... Deterioration of the cables from fatigue, as can happen in running over pulleys, or from corrosion, can be checked by sliding a hand over its length. If a strand of the 7×19 cable is broken, it will “draw blood.” A recurrent problem in all mechanical flight control systems is possible rigging in reverse. This can happen on a new airplane or upon re-rigging an old airplane after disassembly. Modern high-performance sailplanes are generally stored in covered trailers and are assembled only before flying. Sailplane pilots have a keen appreciation of the dangers of rigging errors, including reversals. Preflight checks require the ground crew to resist pilot effort by holding control surfaces and to call out the sense of surface motions, up or down, right or left. A few crossed cable control accidents have occurred on first flights. The aileron cables were crossed for the first flight of Boeing XB-29 No. 2, but the pilot aborted the takeoff in time. Crossed electrical connections or gyros installed in incorrect orientations are a more subtle type of error, but careful preflight procedures can catch them, too. Hydraulic Control Boost. Control boost by hydraulic power refers to the arrangement that divides aerodynamic hinge moment in some proportion between the pilot and a hydraulic cylinder. A schematic for an NACA experimental boosted elevator for the Boeing B-29 airplane shows the simple manner in which control force is divided between the pilot and the hydraulic boost mechanism. Boosted controls were historically the first hydraulic power assistance application. By retaining some aerodynamic hinge moments for the pilot to work against two things are accomplished. First, the control feel of an unaugmented airplane is still there. The pilot can feel in the normal way the effects of high airspeeds and any buffet forces. Second, no artificial feel systems are needed, avoiding the weight and complexity of another flight subsystem. Hydraulic power boost came into the picture only at the very end of World War II, on the late version Lockheed P-38J Lightning, and only on that airplane’s ailerons. After that, hydraulic power boost was the favored control system arrangement for large and fast airplanes, such as the 70-ton Martin XPB2M-1 Mars flying boat, the Boeing 307 Stratoliner, and the Lockheed Constellation series transports, until irreversible power controls took their place. Early Hydraulic Boost Problems. Early hydraulic boosted controls were notoriously unreliable, prone to leakage and outright failures. Among other innovative systems at the time, the Douglas DC-4E prototype airplane had hydraulic power boost. Experience with that system was bad enough to encourage Douglas engineers to face up to pure aerodynamic balance and linked tabs for the production versions of the airplane, the DC-4 or C-54 Sky master. A similar sequence took place at the Curtiss-Wright plant in St. Louis, where the Curtiss C-46Commandowasdesigned.Atagrossweightof45,000 pounds, the C-46 exceeded O.R. Dunn’s rule of thumb of 30,000 pounds for the maximum weight of a transport with leading-edge aerodynamic balance only. Thus, the CW-20, a C-46 prototype, was fitted initially with hydraulic boost having a 3:1 ratio, like those on the Douglas DC-4E Sky master prototype and the Lockheed Constellation. However, maintenance and outright failure problems on the C-46’s hydraulic boost were so severe that the Air Materiel Command decreed that the airplane be redesigned to have aerodynamically balanced control surfaces. The previous successful use of aerodynamic balance on the 62,000-pound gross weight Douglas C-54 motivatedtheAirCorpsdecree.Thiswasthestartofthe“C-46BoostEliminationProgram,” which kept one of this book’s authors busy during World War II. Another airplane with early hydraulically boosted controls was the Boeing 307 Stratoliner. Hydraulic servos were installed on both elevator and rudder controls. Partial jamming of an elevator servo occurred on a TWA Stratoliner. This was traced to deformation of the groove into which the piston’s O ring was seated. The airplane was landed safely. Irreversible Powered Controls. An irreversible power actuator for aerodynamic control surfaces is in principle much simpler than hydraulic control boost. There is no force balancing linkage between the pilot and the hydraulic cylinder to be designed. Irreversible powered controls are classic closed loops in which force or torque is applied until a feedback signal cancels the input signal. They are called irreversible because aerodynamic hinge moments have no effect on their positions. An easily comprehended irreversible power control unit is that in which the control valve body is hard-mounted to the actuation or power cylinder. Pilot control movement or electrical signals move the control valve stem off center, opening ports to the high pressure, or supply hydraulic fluid and low pressure, or sump hydraulic fluid. Piping delivers high-pressure fluid to one side of the piston and low-pressure fluid to the other. The piston rod is anchored to structure and the power cylinder to the control surface. When the power cylinder moves with respect to structure in response to the unbalanced pressure it carries the control valve body along with it. This centers the control valve around the displaced stem, stopping the motion. The airplane’s control surface has been carried to a new position, following up the input to the control valve in a closed-loop manner. The first irreversible power controls are believed to have been used on the Northrop XB-35 and YB-49 flying wing airplanes. Irreversibility was essential for these airplanes because of the large up-floating elevon hinge moment at high angles of attack, as the stall was approached. This was unstable in the sense that pilot aft-yoke motion to increase the angle of attack would suddenly be augmented by the elevon’s own up-deflection. One of the N9MflyingscalemodelsoftheNorthropflyingwingswaslostduetoelevonup-float. The YB-49’s irreversible actuators held the elevons in the precise position called for by pilot yoke position, eliminating up-float. Other early applications of irreversible power controls were to the de Havilland Comet; the English Electric Lightning P1.A, which first flew in 1954; and the AVRO Canada CF-105 Arrow, which first flew in 1958. Howard believes that the Comet application of irreversible powered controls was the first to a passenger jet. The U.K. Air Registration Board “made the key decision to accept that a hydraulic piston could not jam in its cylinder, a vital factor necessary to ensure the failure-survivability of parallel multiple-power control connections to single surfaces.” While irreversible power controls are simple in principle, it was several years before they could be used routinely on airplanes. The high powers and bandwidths associated with irreversible power controls, as compared with earlier boosted controls, led to system limit cycling and instabilities involving support structures and oil compressibility. These problems were encountered and solved in an ad hoc manner by mechanical controls engineer T. A. Feeney for the Northrop flying wings on a ground mockup of the airframe and its control system, called an iron bird. An adequate theory was needed for power control limit cycle instability, to explain the roots of the problem. This was presented by D. T. McRuer at a symposium in 1949 and subsequently published. The post–World War II history of gradual improvements in the design of irreversible power controls is traced by Robert H. Maskrey and W. J. Thayer. They found that Tinsley in England patented the first two-stage electromechanical valve in 1946. Shortly afterwards, R. E. Bayer, B. A. Johnson, and L. Schmid improved on the Tinsley design with direct mechanical feedback from the second-stage valve output back to the first stage. Engineers at the MIT Dynamic Analysis and Controls Laboratory added two improvements to the two-stage valve. The first was the use in the first stage of a true torque motor instead of a solenoid. The second improvement was electrical feedback of the second-stage valve position. In 1950, W. C. Moog, Jr., developed the first two-stage servo valve using a frictionless first-stage actuator, a flapper or vane. Valve bandwidths of up to 100 cycles per second could be attained. The next significant advance was mechanical force feedback in a two-stage servo valve, pioneered by T. H. Carson, in 1953. The main trends after that were toward redundancy and integration with electrical commands from both the pilot and stability augmentation computers. In general, satisfactory irreversible power control designs require attention to many details, as described by Glenn. In addition to the limit cycling referred to previously, these include minimum increment of control, position and time lags, surface positioning accuracy, flexibility, spring back, hysteresis, and irreversibility in the face of external forces. Artificial Feel Systems. Since irreversible power controls isolate the pilot from aerodynamic hinge moments, artificial restoration of the hinge moments, or “artificial feel,” is required. Longitudinal artificial feel systems range in complexity from simple springs, weights, and stick dampers to computer-generated reactive forces applied to the control column by servos. A particularly simple artificial feel system element is the bob weight. The bob weight introduces mass unbalance into the control circuit, in addition to the unbalances inherent in the basic design. That is, even mass-balanced mechanical control circuits have inertia that tends to keep the control sticks, cables, and brackets fixed while the airplane accelerates around them. Bob weights are designed to add the unbalance, creating artificial pilot forces proportional to airplane linear and angular accelerations. They also have been used on airplanes without irreversible power controls, such as the Spitfire and P-51D. The most common bob weight form is a simple weight attached to a bracket in front of the control stick. Positive normal acceleration, as in a pull-up, requires pilot pull force to overcome the moment about the stick pivot of increased downward force acting on the bob weight. There is an additional pilot pull force required during pull-up initiation, while the airplane experiences pitching acceleration. The additional pull force arises from pitching acceleration times the arm from the center of gravity to the bob weight. Without the pitching acceleration component, the pilot could get excessive back-stick motions before the normal acceleration builds up and tends to pull the stick forward. In the case of the McDonnell Douglas A-4 airplane’s bob weight installation, an increased pitching acceleration component is needed to overcome over control tendencies at high airspeeds and low altitudes. A second, reversed bob weight is installed at the rear of the airplane. The reversed bob weight reduces the normal acceleration component of stick force but increases the pitching acceleration component. Another interesting artificial feel system element is the q-spring. As applied to the Boeing XB-47 rudder the q-spring provides pedal forces proportional to both pedal deflection and airplane dynamic pressure, or q. Total pressure is put into a sealed container having a bellows at one end. The bellows is equilibrated by static pressure external to the sealed container and by tension in a cable, producing a cable force proportional to the pressure difference, or q. Pilot control motion moves an attachment point of that cable laterally, providing a restoring moment proportional to control motion and to dynamic pressure. It appears that a q-spring artificial feel system was first used on the Northop XB-35 and B-49 flying wing elevons, combined with a bob weight. Q-spring artificial feel system versions have survived to be used on modern aircraft, such as the elevators of the Boeing 727, 747, and 767; the English Electric Lightning; and the McDonnell Douglas DC-10. Hydraulic rather than pneumatic springs are used, with hydraulic pressure made proportional to dynamic pressure by a regulator valve. In many transport airplanes the force gradient is further modulated by trim stabilizer angle. Stabilizer angle modulation, acting through a cam, provides a rough correction for the center of gravity position, reducing the spring force gradient at forward center of gravity positions. Other modulations can be introduced. Advanced artificial feel systems are able to modify stick spring and damper characteristics in accordance with a computer program, or even to apply forces to the stick with computer-controlled servos. Fly-by-Wire. In fly-by-wire systems control surface servos are driven by electrical inputs from the pilot’s controls. Single-channel fly-by-wire has been in use for many years, generally through airplane automatic pilots. For example, both the Sperry A-12 and the Honeywell The Boeing 767 elevator control system, possibly the last fly-by-cable or mechanical flight control system to be designed for a Boeing transport. Each elevator half is powered by three parallel hydro mechanical servo actuators. Cam overrides and shear units allow separation of jammed system components. C-1 autopilots of the 1940s provided pilot flight control inputs through cockpit console controls. However, in modern usage, fly-by-wire is defined by multiple redundant channel electrical input systems and multiple control surface servos, usually with no or very limited mechanical backup. According to Professor Bernard Etkin, a very early application of fly-by-wire technology was to the Avro Canada CF-105 Arrow, a supersonic delta-winged interceptor that first flew in 1958. A rudimentary fly-by-wire system, with a side-stick controller, was flown in 1954 in a NASA-modified Grumman F9F. The NASA/Dryden digital fly-by wire F-8 program was another early development. You can consult Schmitt and Tomayko for the interesting history of airplane fly-by-wire. The Boeing 767 is probably the last design from that company to retain pilot mechanical inputs to irreversible power control actuators, or fly-by-cable. The 767 elevator control schematic shows a high redundancy level, with three independent actuators on each elevator, each supplied by a different hydraulic system. Automatic pilot inputs to the system require separate actuators, since the primary surface servos do not accept electrical signals. The Boeing 777 is that company’s first fly-by-wire airplane, in which the primary surface servos accept electrical inputs from the pilot’s controls. With the Boeing 777, flyby-wire can be said to have come of age in having been adopted by the very conservative Boeing Company. Fly-by-wire had previously been operational on the Airbus A320, 330, and A340 airplanes shows the redundancy level provided on the Boeing 777 control actuators. PFC refers to primary flight control computers, the ACE are actuator control electronic units, the AFDC are autopilot flight director Controls, the PSA are power supplies, and the FSEU are secondary control units. Note the cross-linkages of the ACEs to the hydraulic power sources. Redundancy level provided on the Boeing 777 Transport. P.F.C. is the primary flight computer, A.C.E. the actuator control electronics, A.F.D.C. the autopilot flight director, P.S.A. the conditioned power, and F.S.E.U. the flap slat electronics unit. McLean gives interesting details on the 777 and A320 fly-by-wire systems: Boeing 777. To prevent pilots exceeding bank angle boundaries, the roll force on the column increases as the bank angle nears 35 degrees. FBW enables more complex inter-axis coupling than the traditional rudder cross feed for roll/yaw coordination which results in negligible sideslip even in extreme maneuvers...the yaw gust damper ...senses any lateral gust and immediately applies rudder to alleviate loads on the vertical fin. The Boeing 777 has an FBW system which allows the longitudinal static margin to be relaxed – a 6 percent static margin is maintained...stall protection is provided by increasing column control forces gradually with increases in angle of attack. Pilots cannot trim out these forces as the aircraft nears stall speed or the angle of attack limit. Airbus 320. Side stick controllers are used. The pitch control law on that aircraft is basically a flight path rate command/flight path angle hold system and there is extensive provision of flight envelope protection...the bank angle is limited to 35 degrees.... There is pitch coordination in turns. A speed control system maintains either VREF or the speed which is obtained at engagement. There is no mechanical backup.... Equipment has to be triplicated, or in some cases quadruplicated with automatic “majority voters” and there is some provision for system reconfiguration. The two cases illustrate an interesting difference in transport fly-by-wire design philosophy. Boeing 777 pilots are not restricted from applying load factors above the limit, except by a large increase in control forces. Wings could be bent in an emergency pullout. Airbus control logic prevents load factors beyond limit. The McDonnell Douglas F/A-18 Hornet represents a move in the direction of completely integrated flight control actuators. Pilot inputs to the F/A-18’s all-moving horizontal tail or stabilator are made through two sets of dual solenoid-controlled valves, a true “fly-by-wire” system. A mechanical input from the pilot is applied only in the event of a series of electrical failures and one hydraulic system failure. The General Dynamics F-16 Integrated Servo Actuator made by the National Water lift Company. This actuator design is typical of an entirely fly-by wire flight control system. The actuator uses mechanical rate and position feedback, although electrical feedback has been tried. Internal hydro mechanical failure detection and correction, using three independent servo valves, causes the piping complexity. The General Dynamics F-16 is a completely fly-by-wire airplane, incorporating fully integrated servo actuators, known by their initials as ISAs. Each actuator is driven by three electrically controlled servo valves. There are no mechanical valve inputs at all from the pilot. Of course, the servo valves also accept signals from a digital flight control computer. The complexity seen in the ISA schematic is due to the failure detection and correction provisions. Only two of the three servo valves operate normally. A first failure of one of these valves shifts control automatically to the third servo valve. A first failure of the third servo valve locks the actuator on the sum of the first two. The F-16 servo actuators also are used as primary surface actuators on the Grumman X29A research airplane. Integrated servo actuators of equivalent technology were developed by Moog, Inc., for the Israeli Lavi fighter airplane. The Northrop/Lear/Moog design for the B-2 Stealth bomber’s flight controls represents another interesting fly-by-wire variant. On this quite large airplane part of the servo control electronics that normally resides in centralized flight control computers has been distributed close to the control surfaces. Digital flight control surface commands are sent by data bus to actuator remote terminals, which are located close to the control surfaces. The terminals contain digital processors for redundancy management and analog loop closure and compensation circuits for the actuators. Distributing the flight control servo actuator feedback functions in this manner saves a great deal of weight, as compared with using centralized flight control computers for this function. Other modern fly-by-wire airplanes include the McDonnell Douglas C-17, the Lockheed Martin F-117 and F-22, the NASA/Rockwell Space Shuttle orbiter, the Antonov An-124, the EF 2000 Eurofighter, the MRCA/Tornado, the Dassault Breguet Mirage 2000 and Rafale, the Saab JAS-39, and the Bell Boeing V-22. Remaining Design Problems in Power Control Systems. The remarkable development of fully powered flight control systems to the point where they are trusted with the lives of thousands of air travelers and military crew persons every day took less than 15 years. This is the time between the Northrop B-49 and the Boeing 727 airplanes. However, there are a few remaining mechanical design problems. Control valve friction creates a null zone in response to either pilot force or electrical commands. Valve friction causes a particular problem in the simple type of mechanical feedback in which the control valve’s body is hard-mounted to the power cylinder. Feedback occurs when power cylinder motion closes the valve. However, any residual valve displacement caused by friction calls for actuator velocity. This results in large destabilizing phase lags in the closed loop. Another design problem has to do with the fully open condition for control valves. This corresponds to maximum control surface angular velocity. That is, the actuator receives the maximum flow rate that the hydraulic system can provide. The resultant maximum available control surface angular velocity must be higher than any demand made by the pilot or an autopilot. If a large upset or maneuver requires control surface angular velocity that exceeds the fully open valve figure, then velocity limiting will occur. Velocity limiting is highly destabilizing. Control surface angles become functions of the velocity limit and the input amplitude and frequency and lag far behind inputs by the human or automatic pilot. The destabilizing effects of velocity limiting have been experienced during the entire history of fully powered control systems. A North American F86 series jet was lost on landing approach when an air-propeller–driven hydraulic pump took over from a failed engine-driven pump. When airspeed dropped off near the runway, the air-propeller–driven pump slowed, reducing the maximum available hydraulic flow rate. The pilot went into a divergent pitch oscillation, an early pilot-induced oscillation event. Reported actuator velocity saturation incidents in recent airplanes include the McDonnell Douglas C-17, the SAAB JAS-39, and the Lockheed Martin/Boeing YF-22. Safety Issues in Fly-by-Wire Control Systems. Although fully fly-by-wire flight control systems have become common on very fast or large airplanes, questions remain as to their safety. No matter what level of redundancy is provided, one can always imagine improbable situations in which all hydraulic or electrical systems are wiped out. Because of the very high-power requirements of hydraulic controls, their pumps are driven by the main engines. This makes necessary long high-pressure tubing runs between the engines and the control surfaces. The long high-pressure hydraulic lines are subject to breakage from fatigue; from wing, tail, and fuselage structural deflections; and from corrosion and maintenance operations. The dangers of high-pressure hydraulic line breakage or leaking, with drainage of the system, could be avoided at some cost in weight and complexity with standby emergency electrically driven hydraulic pumps located at each control surface. An additional safety issue is hydraulic fluid contamination. Precision high-pressure hydraulic pumps, valves, and actuators are sensitive to hydraulic fluid contamination. In view of rare but possible multiple hydraulic and electrical system failures, not to mention sabotage, midair collisions, and incorrect maintenance, how far should one go in providing some form of last-ditch backup manual control? Should airplanes in passenger service have last-ditch manual control system reversion? If so, how will that be accomplished with side-stick controllers? In the early days of hydraulically operated controls and relatively small airplanes the answer was easy. For example, the 307 Stratoliner experience and other hydraulic power problems on the XB-47 led Boeing to provide automatic reversion to direct pilot control following loss in hydraulic pressure on the production B-47 airplanes. Follow-up trim tabs geared to the artificial feel system minimized trim change when the hydraulic system was cut out. Also, when hydraulic power was lost, spring tabs were unlocked from neutral. Manual reversion saved at least one Boeing 727 when all hydraulic power was lost, and a United Airlines Boeing 720 made a safe landing without electrical power. The last-ditch safety issue is less easily addressed for commercial airplanes of the Boeing 747 class and any larger superjumbos that may be built. Both Lockheed L1011 and Boeing 747 jumbos lost three out of their four hydraulic systems in flight. The L1011 had a fan hub failure; the 747 flew into San Francisco approach lights. A rear bulkhead failure in Japan wiped out all four hydraulic systems of another 747, causing the loss of the airplane. In another such incident the crew, headed by Delta Airlines Captain Jack McMahan, was able to save a Lockheed 1011 in 1977 when the left elevator jammed full up, apparently during flight control check prior to takeoff at San Diego. There is no cockpit indicator for this type of failure on the 1011, and the ground crew did not notice the problem. McMahan controlled the airplane with differential thrust to a landing at Los Angeles. This incident was a focus of a 1982 NASA Langley workshop on restructurable controls. Workshop attendees discussed the possible roles of real-time parameter identification and rapid control system redesign as a solution for control failures. Thus, although fully mechanical systems can also fail in many ways, such as cable misrig or breakage, jammed bell cranks, and missing bolts, questions remain as to the safety of modern fly-by-wire control systems. The 1977 Lockheed 1011 incident, a complete loss in hydraulic power in a DC-10 in 1989, and other complete control system losses led to the interesting research in propulsion-controlled aircraft. Managing Redundancy in Fly-by-Wire Control Systems. While redundancy is universally understood to be essential for safe fly-by-wire flight control systems, there are two schools of thought on how to provide and manage redundancy. Stephen Osder defines the two approaches as physical redundancy, which uses measurements from redundant elements of the system for detecting faults, and analytic redundancy, which is based on signals generated from a mathematical model of the system. Analytic redundancy uses real-time system identification techniques, or normal optimization techniques. Physical redundancy is the current technology for fly-by-wire, except for isolated subsystems. The key concept is grouping of all sensors into sets and using the set outputs for each of the three redundant computers. Likewise, each of the computers feeds all three redundant actuator sets. Voting circuitry outputs the mid value of the three inputs to the voting system. Fail-operability is provided, a necessity for fly-by-wire systems. The practical application of physical redundancy requires close attention to communications among the subsystems. Unless signals that are presented to the voting logic are perfectly synchronized in time, incorrect results will occur. In the real world, sensors, computers, and actuators operate at different data rates. Special communication devices are needed to provide synchronization. Additional care is required to avoid fights among the redundant channels resulting from normal error buildup, and not from the result of failures. The situation with regard to analytic redundancy is still uncertain, since broad applications to production systems have not been made. By replacing some physical or hardware redundant elements with software, some weight savings, better flexibility, and more reliability are promised. However, a major difficulty arises from current limitations of vehicle system identification and optimization methods to largely linearized or perturbation models. If an airplane is flown into regions where aerodynamic nonlinearities and hysteresis effects are dominant, misidentification could result. Misidentification with analytic redundancy could also arise from the coupled nature of the sensor, computer, and actuator subsystems. Osder gives as an example a situation where an actuator position feedback loop opening could be misdiagnosed as a sensor failure, based on system identification. An analytic redundancy application to reconfiguring a system with multiple actuators is given by Jiang. The proposed system uses optimization to reconfigure a prefilter that allocates control among a set of redundant actuators and to recompute feedback proportional and integral gains. A somewhat similar analytic redundancy scheme, using adaptive control techniques, is reported by Hess. Baumgarten reported on reconfiguration techniques focusing on actuator failures. The best hope for future practical applications of analytical redundancy rests in heavy investments in improved methods of system identification. This appears to be the goal of several programs at the Institute of Flight Mechanics of the DLR. Electric and Fly-by-Light Controls. Fully electrical airplane flight control systems are a possibility for the future. Elimination of hydraulic control system elements should increase reliability. Failure detection and correction should become a simple electronic logic function as compared with the complex hydraulic arrangement seen in the F-16’s ISA. Fly-by-light control systems, using fiber optic technology to replace electrical wires, are likewise a future possibility. Advanced hardware of this type requires no particular advances in basic stability and control theory.

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Flying Qualities Becomes a Science

The stability and controllability of airplanes as they appear to a pilot are called flying or handling qualities. It was many years after airplanes first flew that individual flying qualities were identified and ranked as either desirable or unsatisfactory. Even more time passed before engineers had design methods connected with specific flying qualities. A detailed and fascinating account of the early work in this area of Stanford University Professor Walter G. Vincent’s scholarly book What Engineers Know and How They Know It. We pick up the story in 1919, with the first important step in the process that made a science out of airplane flying qualities.

Vincenti found that the first quantitative stability and control flight tests in the United States occurred in the summer of 1919. MIT Professor Edward P.Warner, working part time at the NACA Langley Laboratory, together with two NACA employees, Frederick H. Norton and Edmund T. Allen, made these tests using Curtiss JN-4H “Jennies” and a de Havilland DH-4. They made the most fundamental of all stability and control measurements: elevator angle and stick force required for equilibrium flight as a function of airspeed.

Warner and Norton made the key finding that the gradient of equilibrium elevator angle with respect to airspeed was in fact an index of static longitudinal stability, the tendency of an airplane to return to equilibrium angle of attack and airspeed when disturbed. The elevator angle–airspeed gradient thus could be correlated with the 1915–1916 MIT wind-tunnel measurements by Dr. Jerome C. Hunsaker of pitching moment versus angle of attack on the Curtiss JN-2, an airplane similar to the JN-4H. In the words of Warner and Norton:

If an airplane which is flying with the control locked at a speed corresponding to the negatively sloped portion of the elevator position curve is struck by a gust which decreases its angle of attack, the angle will continue to decrease without limit. If the speed is low enough to lie on the positively sloping portion of the curve, the airplane will return to its original speed and angle of trim as soon as the effect of the gust has passed.

A strange aspect of the Warner and Norton JN-4H test results was the effect of airspeed on static longitudinal stability. The JN-4H was stable at airspeeds below about 55 miles per hour and unstable above that speed. One would be tempted to look for an aero elastic cause for this, except that wind-tunnel tests of a presumably rigid model showed the same trend. The cause remains a mystery. The 1915–1916 MIT wind-tunnel tests were supplemented in 1918 by the U.S. Air Service at McCook Field with JN-2 wind-tunnel tests, in which the model had an adjustable elevator angle.

  The McCook Field group was active in stability and control flight tests at the same period.

As part of an armed service procurement activity, McCook’s primary interest was in airplane suitability for military use, rather than in aeronautical research. Thus, it is understandable that there were no measurements at the level of sophistication of the Norton and Allen tests at the NACA. Captain R. W. Schroeder was one of the Air Service’s top test pilots. His 1918 report on the Packard-Le Pere LUSAC-11 fighter airplane’s handling qualities was completely qualitative.

In the course of the pioneering stability and control flight tests at the NACA Langley Laboratory, instrumentation engineers including Henry J. E. Reid, a future Engineer-in-Charge at Langley, came up with specialized devices that could record airplane motions automatically, freeing pilots from having to jot down data while running stability and control flight tests. Langley Laboratory individual recording instruments developed in the 1920s measure control positions, linear accelerations, airspeed, and angular velocities.

Warner and Norton’s measurements of elevator angles required to trim as a function of airspeed and power for the Curtiss JN4H airplane. They correctly interpreted the data to show static longitudinal instability at airspeeds above the peaks of the curves.

In each recording instrument, a galvanometer-type mirror on a torsion member reflects light onto a photographic film on a drum. A synchronizing device keys together the recordings of individual instruments, putting timing marks on each drum. Frederick Norton said in later years that the work at Langley in which he took the most pride was the development of these specialized flight recording instruments.

The instrument developments put NACA far in front of other groups in the United States who were working on airplane stability and control. The photo recorder was typical technology at other groups running stability and control tests, such as the U.S. Army Air Corps Aircraft Laboratory at Wright Field. In the photo recorder, stability measurement transducers, ordinary flight instruments, and a stopwatch are mounted in a bulky closed box and photographed by a movie camera. Data are then plotted point by point by unfortunate technicians or engineers reading the film.

As another indication of NACA’s advanced flying qualities measurement technology, one of this book’s authors who served in the U.S. Navy during World War II remembers having to borrow a stick force measuring grip from NACA to run an aileron roll test on a North American SNJ trainer.

NACA flying qualities research in the 1920s and early 1930s also trained a group of test pilots, including Melvin N. Gough, William H. McAvoy, Edmund Allen, and Thomas Carroll, in stability and control research techniques, including the ability to reach and hold equilibrium flight conditions with accuracy. As with all good research test pilots, the NACA group worked closely with flight test engineers and in fact took part in discussing NACA’s flying qualities work with outsiders. All of this helped lay the groundwork for the comprehensive flying qualities research that followed.

Edward P. Warner, acting as a consultant to the Douglas Aircraft Company in the design of the DC-4E transport, has the distinction of having first embodied flying qualities research into a specification that could be applied to a new airplane design, much as characteristics such as strength and performance had been specified previously. Warner’s 1935 requirements were based on interviews with airline pilots, industrial and research test pilots, and NACA staff engineers. Warner also recognized the need to put flying qualities requirements on a sounder basis by instrumented flight tests correlated with pilot opinions.

Warner’s ideas were picked up by the NACA and the grand comprehensive attack on airplane flying qualities started. The authorizing document was NACA Research Authorization number 509, “Preliminary Study of Control Requirements for Large Transport Aircraft”. Hartley A. Soule´ a portly, worldly-wise staff member at the NACA Langley Aeronautical Laboratories in Hampton, Virginia, ran tests the following year that attempted to correlate the long-period longitudinal or phugoid mode of motion with pilots’ opinions on handling qualities. The phugoid motion involves large pitch attitude and height changes at essentially constant angles of attack. Eight single-engine airplanes were tested by Soulé and his group. This pioneering attempt showed that neither period nor damping of the phugoid motion had any correlation with pilot opinion.

However, the NACA was fairly launched on the idea of correlating flying qualities measurements with pilots’ opinions. Soulé and his associate, Floyd L. Thompson, outlined the practical steps needed to carry out Warner’s ideas. Flying qualities had to be defined “in terms of factors known to be susceptible of measurement by existing NACA instruments or by instruments that could be readily designed or developed.”

 Thompson and Soulé started with what we would now call a set of “straw man” requirements based on Warner’s work, but modified to be measurable by NACA’s instruments. They used a Stinson Reliant SR-8E single-engined high-wing cabin airplane for the tests. It turned out that the only instruments that needed to be specially developed for the Stinson tests were force-measuring control wheel and rudder pedals. These used hydraulic cells developed by the Bendix Corporation as automobile brake pedal force indicators.

The “straw man” NACA requirements seemed to ignore Soulé’s previous findings of the unimportance of the longitudinal phugoid motion, and a reasonably well-damped oscillation of period not less than 40 seconds was specified. Even more curiously, F. W. Lanchester’s research on the phugoid period was quite over looked in the straw man requirements, although Lanchester’s results were given in the well-known 1934 “Dynamics of the Airplane,” by B. Melvill Jones, which was included in Volume V of W. F. Durand’s Aerodynamic Theory. Lanchester had shown that the phugoid period for all aircraft was linearly proportional to airspeed and would invariably fall below the required 40 seconds at airspeeds under about 150 miles per hour.

Aside from this cavil, Soulé’s research followed reasonable lines. Each straw man requirement was stated, test procedures to check each requirement were spelled out, and the test results were presented and discussed. Some of Soulé’s 1940 test procedures have come down to our day virtually unchanged except for the increased sophistication of data recording. For example, there were measurements of elevator angle and stick force for equilibrium flight at various airspeeds, measurements of time to bank to a specified angle, and, most advanced of all, measurements of the period and damping of the phugoid oscillation as a function of airspeed.

In his published report Soulé’s provides the variations with airspeed for equilibrium flight of both the elevator angle and the control column position from the dashboard. These data would give exactly the same trends were it not for stretch of the control cables that connect the two, under load. Vincenti’s book tells the interesting story of the discovery of the effects of cable stretch on the Stinson data.

Soulé’s report was reviewed in preliminary form by engineers at the Chance Vought Aircraft plant in Connecticut, who noticed that different incidence settings of the horizontal tail affected the variations in elevator angle for equilibrium flight, an unexpected outcome. C. J. McCarthy of Chance Vought wrote to Soulé’s suggesting that the discrepancy might be explained by control cable stretch if the elevator angle had been deduced from the control column position, rather than having been measured directly at the surface itself. According to Vincenti:  

Robert R. Gilruth, a young engineer who had recently taken over the flying quality program when Soulé’s moved to wind tunnel duties, measured the stretch under applied load sand found that Chance Vought’s supposition was in fact correct. In tests of later airplanes, elevator angles were measured directly at the elevator. Such matters seem obvious in retrospect, but they have to become known somehow.

Some Stinson measurements called for by the straw man requirements are definitely archaic and not a part of modern flying qualities. Very specific requirements were put on the time needed to change pitch attitude by 5 degrees; these were checked. Likewise, the need to limit adverse yaw in aileron rolls was dealt with by measuring maximum yawing acceleration and comparing it with rolling acceleration. The yaw value was supposed to be less than 20 percent of the roll value. However, all of the pieces were in place now and ready for the next major step.

After the Stinson tests the NACA had the opportunity to test a large airplane, the Martin B-10B bomber. Those results went to the Air Corps in a confidential report of 1938. According to Vincenti, Edward Warner was able to feedback both the Stinson SR-8E and Martin B-10B results to his flying qualities requirements for the Douglas DC-4E, which was just beginning flight tests.

Robert R. Gilruth came to NACA’s Langley Laboratory in 1937 from the University of Minnesota. His slow, direct speech reflected his Midwestern origins. He is remembered for a remarkable ability to penetrate to the heart of problems and to convince and inspire other people to follow his lead. When Gilruth fixed one with a penetrating stare and, with a few nods, explained some point, there was not much argument. Many years later, when NACA became NASA, Gilruth was tapped by the government to head the NASA Manned Spacecraft Center.

Gilruth’s seminal achievement was to rationalize flying qualities by separating airplanes into satisfactory and unsatisfactory categories for some characteristic, such as lateral control power, by pilot opinion. He then identified some numerical parameter that could make the separation. That is, for parameter values above some number, all aircraft were satisfactory, and vice versa. The final step was to develop simplified methods to evaluate this criterion parameter, methods that could be applied in preliminary design.

 The great importance of this three-part method is that engineers now could design satisfactory flying qualities into their airplanes on the drawing board. Although proof of good flying qualities still required flight testing, engineers were much less in the dark. The old way of doing business is illustrated by an NACA report on the development of satisfactory flying qualities on the Douglas SBD-1 dive bomber. Discussing a Phase III series of tests in September 1939, the report said, “The best configuration from this phase was submitted to a pilot representative from the Bureau, who considered that insufficient improvements had been made. 

Two applications of this new method were published by Gilruth and co-authors Maurice D. White and W. N. Turner to static longitudinal stability and to lateral control power, respectively. White had joined Gilruth at Langley in 1938. Fifteen airplanes ranging in size from the Aeronca K to the Boeing B-15 were tested in the first series, on longitudinal stability. Gilruth and White suggested a design value of 0.5 for the gradient of elevator angle with angle of attack, for the propeller-idling condition, to ensure power-on stability and adequate stick movement in maneuvers.

In the lateral control application of the new method, 28 different wing–aileron combinations were tested, including alterations to the wings and ailerons of two of the airplanes tested. The famous lateral control criterion function pb/2V came into being as a result of this work. Pb/2V is the helix angle described by a wing tip during a full-aileron roll. Gilruth and Turner fixed the minimum satisfactory value of the full-aileron pb/2V as 0.07, expressed in radian measure. A remarkably simple preliminary design estimation technique for pb/2V was presented, based on a single-degree-of-freedom model for aileron rolls.

Robert Gilruth’s early flying qualities work was closed out with publication of “Requirements for Satisfactory Flying Qualities of Airplanes.” This work had appeared in classified form in April 1941. A three-part format was used. First, the requirement was stated. Then there were reasons for the requirement, generally based on flight tests. Finally, there were “Design Considerations” related to the requirement, the all-important methods that would permit engineers to comply with the requirements for ships still on the drawing board.

Gilruth’s 1943 work introduced the concept of the pilot’s stick deflection and force in maneuvers and the criteria of control deflection per g and stick force per g. Vincenti points out that the control deflection and stick force per g criteria may have been independently conceived in Britain by S. B. Gates. Prior to the Gilruth/Gates criteria, stability and control dealt with equilibrium or straight flight conditions. W. H. Phillips calls this quantization of maneuverability one of Gilruth’s most important contributions to airplane flying qualities.

Sidney Barrington Gates had a remarkable career as an airplane stability and control expert in Britain, spanning both World Wars. He left Cambridge University in 1914, in his words, “as an illegitimate member of the Public Schools Battalion of the Royal Fusiliers.” Somebody with unusual perception for those days saw that the young mathematician belonged instead in the Royal Aircraft Factory, the predecessor of the Royal Aircraft Establishment or RAE, and he was transferred there.

Sidney B. Gates, contributor to understanding of airplane spins; originator of neutral and maneuver points, stick force per g, and many other flying qualities matters.

Gates remained at the RAE and as a committee member of the Aeronautical Research Council until his retirement in 1972. His total output of papers came to 130, a large proportion of which dealt with airplane stability and control. His approach to the subject is described by H. H. B. M. Thomas and D. Ku¨chemann in a biographical memoir, as follows:

Gates’s life-long quest – how to carve a way through the inevitably harsh and complex mathematics of airplane motion to the shelter of some elegantly simple design criterion based often on some penetrating simplification of the problem.

This approach is seen at its best in his origination of the airplane static and maneuver margins, simple parameters that predict many aspects of longitudinal behavior. He gave the name “aerodynamic center” to the point on the wing chord, approximately 1/4 chord from the leading edge, where the wing pitching moment is independent of the angle of attack. The wing aerodynamic center concept led to current methods of longitudinal stability analysis, replacing wing center of pressure location.

Gates is also remembered for a long series of studies on airplane spinning, begun with “The Spinning of Aero planes”, co-authored with L. W. Bryant. Gates’ other airplane stability and control contributions over his career cover almost the entire field. They include work in parameter estimation, swept wings, VTOL transition and flying qualities requirements, handling characteristics below minimum drag speed, transonic effects, control surface distortion, control friction, spring tabs, lateral control, landing flap effects, and automatic control.

Together with Morien Morgan, in 1942 Gates made a two-month tour of the United States, “carrying a whole sack load of RAE reports on the handling characteristics of fighters and bombers.” The pair met with the main U.S. aerodynamics researchers and designers at the time, including Hartley Soule´, Gus Crowley, Floyd Thompson, Eastman Jacobs, Robert Gilruth, Hugh Dryden, Courtland Perkins, Walter Diehl, Jack Northrop, Edgar Schmued, W. Bailey Oswald, George Schairer, Kelly Johnson, Theodore von K´arma´n, and Clark Millikan. As Morgan comments, the scope and scale of the 1942 “dash around America” showed what a towering reputation Gates had worldwide.

The U.S. Military Services Follow NACA’s Lead.

Following NACA’s lead, both the U.S. Air Force and the U.S. Navy Bureau of Aeronautics issued flying qualities specifications for their airplanes. Indeed, after the war, the allies discovered that the Germans had established military flying qualities requirements at about the same time. In April 1945 the U.S. Air Force and Navy coordinated their requirements, recognizing that some manufacturers supplied airplanes to both services. The coordinated Air Force specification got the number R-1815-A; the corresponding Navy document was SR-119A. In 1948 the final step was taken and the services put out a joint military flying qualities specification, MIL-F-8785. This document went through many subsequent revisions, the most significant of which was the 1969 MIL-F-8785B.

The main difference between Gilruth’s NACA requirements and the military versions was in the detailed distinctions made by the military among different types of aircraft. For example, in the military version, maneuvering control force, the so-called stick force per g, was generalized to apply to airplanes with any design limit load factor. NACA had recognized only two force levels, for small airplanes with stick controls and for large ones with wheel controls. Special requirements were given in the joint specification for aircraft meant to fly from naval aircraft carriers. MIL-F-8785 and its revisions were incorporated into the procurement specifications of almost all military aircraft after 1948.

The transformation of one particular flying qualities requirement from the original NACA or Gilruth version through successive military specifications can be traced. This requirement is for the longitudinal short-period oscillation. The longitudinal short period is a relatively rapid oscillation of angle of attack and pitch attitude at relatively constant airspeed. The original NACA requirement applies to the stick-free case only, as follows:

When elevator control is deflected and released quickly, the subsequent variation of normal acceleration and elevator angle should have completely disappeared after one cycle.

Gilruth goes on to give reasons for this requirement, as follows:

The requirement specifies the degree of damping required of the short-period oscillation with controls free. A high degree of damping is required because of the short period of the motion. With airplanes having less damping than that specified, the oscillation is excited by gusts, thereby accentuating their effect and producing unsatisfactory rough-air characteristics. The ratio of control friction to air forces is such that damping is generally reduced at high speeds. When the oscillation appears at high speeds as in dives and dive pull-outs, it is, of course, very objectionable because of the accelerations involved.

The first U.S. Air Force specification, C-1815, relaxed the NACA requirement, allowing complete damping in two cycles instead of one. This was done because opinions collected from Air Force pilots and engineers were that the response with the stick fixed was always satisfactory, and so the short-period oscillation was of no importance in design. However, by the time of a 1945 revised specification, R-1815-A, further experience led back to the original NACA requirement of complete damping for the stick-free case in one cycle. A refinement to an analytically more correct form, one better suited for design and flight testing, was made in the next revision, R-1815-B. This is damping to 1/10 amplitude in one cycle, corresponding to a dimensionless damping ratio of 0.367.

Modern design trends, especially higher operating altitudes and wing loadings, decreased the damping in the stick-fixed case, while with irreversible controls the stick-free case essentially disappeared. When the initial stick-fixed damping requirements were set, in MILF-8785, the level was set at a damping ratio of 0.110, or damping to a half-amplitude in one cycle. This relatively low damping requirement is based on NACA experience with research airplanes, whose pilots seem agreeable to low damping levels. As service experience was gained with high-altitude, dense airplanes the trend was reversed and damping requirements were increased again.

This uncertainty in the desirable level of longitudinal short-period damping was typical of what led to ambitious, reasonably well-funded Air Force and Navy research programs to rationalize the flying qualities data base. In the United States, flying qualities flight and ground simulator testing went on all over the country, especially at the NACA laboratories, the Cornell Aeronautical Laboratory, Systems Technology, Inc., NATC Patuxent River, Wright Field, and at Princeton University. British, German, Dutch, and French laboratories also became active in flying qualities research at this time.

Under U.S. Air Force sponsorship, the Cornell Aeronautical Laboratory used a variable-stability jet fighter to make a systematic attack on the longitudinal short-period damping question. Robert P. Harper and Charles R. Chalk ran experiments with variations in short period damping and frequency at constant levels of stick force and displacement per unit normal acceleration. They found a “bull’s-eye” of good damping and natural frequency combinations, surrounded by regions of acceptable to poor performance.

This and similar efforts went into successive revisions of MIL-F-8785, reaching at last the “C” revision of November 1980. All along, the specification writers were guided by peer reviews and conferences involving specification users in the industry. At one point, the U.S. Navy Bureau of Aeronautics requested Systems Technology, Inc. to search for weaknesses in the specification. The resultant report was issued with the attention getting title, “Outsmarting MIL-F-8785.” Good summaries of the revision work may be found in Chalk and Ashkenas.

Civil Airworthiness Requirements.

Military aircraft are procured under comprehensive flying qualities specifications. These specifications are contractual obligations by the manufacturer to a single military customer. On the other hand, the flying qualities of commercial aircraft are generally not governed by contracts with individual customers, but rather by governmental agencies, acting to protect the flying public.

Civil flying qualities requirements are found in airworthiness requirement documents. Compliance with airworthiness standards is proved in flight testing, leading to the award of airworthiness certificates and freedom to market the aircraft. Civil airworthiness requirements are the minimum set that will ensure safety. This is a different objective than military requirements, which not only address safety, but also the effectiveness of military airplanes in their missions. Thus, flying qualities requirements found in civil airworthiness requirements are much less detailed than specified requirements for military airplanes. This is a key distinction between the two sets of requirements.

World-Wide Flying Qualities Specifications.

As mentioned earlier, the German air forces in World War II operated under a set of military flying qualities requirements related to the Gilruth set of 1943. The growth of civil aviation after the war led to a number of national and world-wide efforts to specify flying qualities requirements, in order to rationalize aircraft design and procurement in each country and the international licensing of civil aircraft. The goal of internationally agreed upon civil aircraft flying qualities standards is the responsibility of the International Civil Aviation Organization, an arm of the United Nations. Annex 8 of the ICAO Standards deals with airworthiness, which includes adequate flying qualities.

 Standards have also been adopted by individual countries for both civil and military machines. An earlier section traced the evolution of U.S. flying qualities specifications for military aircraft. Similar evolutions took place all over the world. British military specifications are in the UK DEF STAN publications. In particular, DEF-STAN 00-970, issued in 1983, is similar in style to MIL-F-8785C and provides much the same information.

British civil flying qualities requirements were embodied initially in the BCARs, or British Civil Airworthiness Requirements. European standards now apply, as found in the European Joint Aviation Requirements, or JARs, issued by the Joint Aviation Administration. The U.S. versions are the Federal Air Regulations, or FARs, parts 21, 23, 25, and 103 of which deal with airplanes. The wording of the stability and control airworthiness requirements of the FARs is similar to the Gilruth requirements of 1943, which were also concerned with minimum rather than optimum requirements.

Equivalent System Models and Pilot Rating.

The 1980 military flying qualities specification MIL-F-8785C represents the culmination of the representation of airplanes by classical transfer functions, the transfer functions of bare airframes augmented only by simple artificial damping and cross feeds, where needed. In pitch, the bare airframe transfer function of pitching velocity as an output to control surface angle as an input has an inverse second-order denominator and a first-order numerator under the constant airspeed assumption. Three parameters define this function: natural frequency and damping ratio in the denominator and the numerator time constant. The classical bare-airframe transfer function models are called equivalent systems because they can only approximate the transfer functions of complex, augmented flight control systems, such as command augmentation systems and the newer super augmented systems for highly unstable airframes.

The 1980 specification MIL-F-8785C represented another culmination in the development of airplane flying qualities as a science. This is assigning a numerical scale to pilot opinion. In the 1950s A. G. Barnes in the United Kingdom used the initials G, M, and B for good, medium, and bad, with + and − modifiers. The numerical scale, running from 1 to 10, was proposed by George E. Cooper in 1961. The MIL-F-8785C uses the Cooper-Harper rating scale, in which the experience of NASA and Cal span are combined.

A successor to the Cooper-Harper rating scale originated at the College of Aeronautics, Cranfield University to deal better with modern fly-by-wire aircraft. The proposed new scale, called the Cranfield Aircraft Handling Qualities Rating Scale, or CAHQRS, considers separately five parameters – longitudinal, lateral, directional, trim, and speed control – and rates behavior in subtasks according to a Cooper-Harper-type scale, and also a criticality scale. The CAHQRS has been tested initially on a flight simulator. Further experience with this new approach is needed to confirm its expected benefits relative to the Cooper-Harper standard.

The next phase in the unfolding history of the science of flying qualities involves a new level of sophistication, freeing the subject from the constraint of equivalent systems. Mathematical models of the human pilot as a sort of machine are combined with airplane and control system mathematical models and are treated as a combined system. Human physiology and psychology are now enlisted in the study of flying qualities requirements.

The Counterrevolution.

In the late 1980s a counterrevolution of sorts took place, a retreat from authoritative military flying qualities specifications. A new document, called the Military Standard, Flying Qualities of Piloted Vehicles, MIL-STD-1797, merely identifies a format for specified flying qualities. Actual required numbers are filled into blanks through negotiations between the airplane’s designers and the procurement agency. As explained by Charles B. Westbrook, the idea was to let MIL spec users know that “we didn’t have it all nailed down, and that industry must use some judgment in making applications.”

A large handbook accompanies the Military Standard, giving guidance on blank filling and on application of the requirements. The handbook is limited in distribution because its “lessons learned” includes classified combat airplane characteristics. The Military Standard development for flying qualities is associated with Roger H. Hoh of Systems Technology, Inc., and with Westbrook, David J. Moor house, and the late Robert J. Woodcock, of Wright Field.

The demise of the authoritative MIL-F-8785 specification was part of a general trend away from rigid military specifications, with the intent of reducing extraneous and detailed management of industry by the government. Industry designers said in effect, “Get off our backs and let us give you a lighter, better, cheaper product” and “Quit asking for tons of reports demonstrating compliance with arcane requirements.” Some horror stories brought out by the industry people did seem to make the point. The Military Standard is in fact ideal for “skunk works” operations; their managers don’t like more than general directions.

 However, the Military Standard seems to bring back the bad old days, the “straw man” requirements of the 1930s, established by pilots and engineers based on hunch and specific examples. It is as if the rational Gilruth method had never been invented. A justification of sorts for the counterrevolution is the tremendous flexibility provided stability and control designers with the new breed of digital flight control systems.

 Literally, it is now possible to have an airplane with any sort of flying qualities that one can imagine. Tiny side sticks can replace conventional yoke or stick cockpit controls. Right or left stick or yoke controls no longer have to apply rolling moments to the airplane. Instead, bank angle, constant rolling velocity, or even heading change can now be the result. By casting off the bonds of the rigid MIL-F-8785 specification, a procuring agency can take advantage of radical, innovative control schemes proposed by contractors.

  The ability of advanced flight control systems to provide any sort of flying qualities that can be imagined brought a cautionary note from W. H. Phillips, as follows:

The laws of nature have been very favorable to the designers of control systems for old-fashioned subsonic, manually-controlled airplanes. These systems have many desirable features that occur so readily that their importance was not realized until new types of electronic control systems were tried.

 Don Berry, a senior engineer at the NASA Dryden Research Center, had similar views:

We have systems capable of providing a wide variety of control responses, but we are not sure what responses or modes are desirable.

 A further step in the dismantling of “rational” Gilruth flying qualities specifications is the recent appearance of independent assessment boards, charged with managing the flying qualities levels of individual airplanes. Such a board, called the “Independent Assessment Team,” was formed for the Navy’s new T-45A trainer. Team members for the T-45A included the very senior, experienced engineers William Koven, I. Grant Hedrick, Joseph R. Chambers, and Jack E. Linden.

Procurement Problems.

 In either case, whether airplane flying qualities are specified by a standardized specification such as MIL-F-8785 or by negotiations involving a Military Standard, there is still the matter of getting new airplanes to meet flying qualities requirements. In other words, the science of flying qualities is useless unless airplanes are held to the standards developed by that science.

 In recent years, new airplanes are being bought by the U.S. armed services in a way that seems designed for poor flying qualities. Program officers are given sums of money sufficient to produce a fixed number of airplanes on a schedule. Military careers rest on meeting costs and schedules. These are customarily optimistic to begin with, having gotten that way in order to sell the program against competing concepts or airplanes.

 The combination of military career pressures and optimistic cost and schedule goals usually leads to the dreaded “concurrency” program. Production tooling and some manufacturing proceed concurrently with airplane design and testing, rather than after these have been completed. When flying quality deficiencies crop up late in a concurrent program, requiring modifications to tooling and manufactured parts, it is natural for program officers and their counterparts in industry to resist.

 Three notable recent concurrent programs were the Lockheed S-3 Viking anti-submarine airplane, the Northrop B-2 stealth bomber, and the U.S. naval version of the British Aerospace Hawk trainer, being built by McDonnell Douglas/Boeing. The Lockheed S-3 and McDonnell Douglas/Boeing T-45A concurrency stories are involved with the special flying qualities requirements of carrier-based airplanes, on that subject.  

Variable-Stability Airplanes Play a Part.

 A variable-stability airplane is a research airplane that can be made to have artificially the stability and control characteristics of another airplane. Waldemar O. Breuhaus credits this invention to William M. Kauffman, at the NASA Ames Research Center, about the year 1946. The colorful story that Breuhaus tells is of Kauffman looking out of the window at the Ames flight ramp and seeing three Ryan FR-1 Fireball fighters sitting side by side. Each FR-1 had a different wing dihedral angle. The airplanes had been so modified to try to find in flight testing the minimum amount of effective dihedral angle that pilots would accept. Kauffman said, according to Steve Belsley and some others, “There has to be a better way.”

 Ames modified a Grumman F6F-3 Hellcat into the first variable-stability airplane by a mechanism that moved the ailerons in response to measured sideslip angles. An electric servo motor, adapted from a B-29 gun turret drive, moved the F6F’s aileron push–pull rods in parallel to the pilot’s stick input. With this parallel arrangement, the pilot’s stick is carried along when the servo works in response to measured sideslip. This is suitable for automatic pilots, where it is often acceptable and even desired for the pilot’s controls to reflect automatic pilot inputs. However, it does not serve the function of a variable-stability airplane, where the action of the variable-stability mechanism is supposed to be unnoticeable to the pilot.

 In the case of the pioneering F6F-3 variable-stability airplane, pilot stick motions were suppressed approximately by an ingenious scheme that canceled the aerodynamic hinge moment corresponding to the commanded aileron deflection. This was done by driving the aileron tab through its own servo motor with a portion of the same signal that was used to drive the aileron push–pull rod.

 The F6F-3 variable-stability airplane was followed in the next 30 years by at least 20 other airplanes of the same type. The majority were built by NACA/NASA; the Cornell Aeronautical Laboratories, later Cal span; the German Aerospace Center, or DLR; and the Royal Aircraft Establishment, later DERA. Princeton University, the Canadian National Research Council, Boeing, and research agencies in France and Japan also built them.

 The crude compromises of the early machines have given way to ever more sophisticated ways of varying airplane stability and control as seen by the test pilot. Later models, such as the Cal span Total In-Flight Simulator, or TIFS, and the Princeton University Variable Response Research Aircraft, or VRA, have special side-force generating surfaces.            

Variable-Stability Airplanes as Trainers

The objectives of most of the variable-stability programs were either to apply the Gilruth method of obtaining flying qualities requirements by exposing pilots to different stability and control levels or to present the flying characteristics of a future machine for evaluation. However, quite by chance, a different use for variable-stability airplanes cropped up. Breuhaus reports that Gifford Bull, the project engineer and safety pilot of a Cal span variable-stability USAFB-26 airplane, was chatting with members of the Navy Test Pilot School at the Patuxent River Naval Air Test Center. The B-26 was at Patuxent to run Navy-sponsored tests on minimum flyable longitudinal handling qualities under emergency conditions. Test Pilot School staffers were struck by what looked like

the unique suitability of the variable stability airplane to serve as a flying class room or laboratory to demonstrate to the school the effects of the myriad flying quality conditions that could be easily and rapidly set up.

A trial run in 1960 was such an instant success that the program was broadened to include the Air Force Test Pilot School at Edwards Air Force Base, and a second B-26 was added. The aging B-26s were eventually replaced by two variable-stability Learjet Model 24s. By the end of 1989 nearly 4,000 service, industrial, and FAA pilots and engineers had instruction or demonstrations using the variable-stability B-26s and Learjet’s.

 In a more recent application of an airplane modified to fly like another airplane for training, NASA used a Grumman Gulfstream G-2 in a high drag configuration to train pilots to fly the Space Shuttle’s steep, fast-landing approach profile, starting at an altitude of about 30,000 feet.

  The Future of Variable-Stability Airplanes.

 The engineers at NASA, Cal span, DERA, the Canadian NRC, Princeton University, and other European and Asian laboratories who had so much to do with the development of variable-stability airplanes can point to impressive accomplishments using these devices. Variable-stability airplanes shed light on many critical issues, such as the role of roll-to-yaw ratios on required Dutch roll damping, permissible levels of spiral divergence, and the effect of longitudinal flying qualities on instrument landing system landing approaches. Variable-stability airplanes have also provided a preliminary look at the flying qualities of radical new airplanes such as the Convair B-58 Hustler; the Rockwell X-15, XB-70, B-1, and Space Shuttle Orbiter; the Lockheed A-12 and F-117A; the Grumman X-29A; various lifting body projects; and the Anglo-French Concorde before those new airplanes flew.

 The TIFS machine, based on a reengined Convair C-131 Btransport, has had a particularly productive career. Cal span engineers provided the TIFS with the ability to add aerodynamic forces and moments to all 6 degrees of freedom. Flight tests are carried out from an evaluation cockpit built into the airplane’s nose, while a safety crew controls the airplane from the normal cockpit. Some 30 research programs have been run on this airplane. The majority of them were general flying qualities research; ten programs were on specific airplanes. A T-33 variable-stability airplane also had a very productive career, with more than 8,000 flying hours to date. A new application of variable-stability airplanes has been reported from the DLR, in which the ATTAS in-flight simulator investigated manual flight control laws for a future 110-seat Airbus transport airplane.

 In spite of this impressive record, there are reasons to look for limitations in the future use of variable-stability airplanes in the engineering development of new aircraft. A significant obstacle is the practical difficulty in updating and maintaining the vast computer data bases needed to represent the mathematical models of complex digital flight control and display systems and nonlinear, multivariable aerodynamic data bases. Maintaining current data bases should be inherently easier for locally controlled ground-based simulators, as compared with variable-stability airplanes operated by another agency at a remote site.

 Another limitation to the future use of variable-stability airplanes in the engineering development of specific air planes has to do with the cockpit environment. Correctly detailed controls, displays, and window arrangements, important for a faithful stability and control simulation, may be difficult to provide on a general-purpose variable-stability airplane. Correct matching of accelerations felt by the pilot is also desirable. Although variable-stability airplanes do provide the pilot with both acceleration and visual cues, both cannot be represented exactly, along with airplane motions, unless the variable-stability machine flies at the same velocity as the airplane being simulated and unless the pilot is at the same distance from the airplane’s center of gravity in both cases.

 Those conditions are rarely satisfied, except in some landing approach simulations. For example, the Princeton University VRA, flying at 105 knots, has been used to simulate the Space Shuttle Orbiter flying at a Mach number of 1.5. Pilot acceleration cues can be retained under a velocity mismatch of this kind by a transformation of variable-stability airplane outputs that amounts to using a much higher yaw rate. Likewise, pilot location mismatch is conveniently corrected for by a transformation on the sideslip angle. If these transformations are applied to correct pilot acceleration cues, visual cues will be made incorrect. An alternative scheme to provide correct pilot acceleration cues relies on the direct side and normal force capabilities of advanced machines such as the TIFS.

 In general, the cockpit environment of a new airplane can be represented fairly readily in a ground-based simulator. Correct visual cues can be provided as well, although there are often troubling lags in projection systems. The major loss in fidelity for ground simulators, as compared with variable-stability airplanes, comes from the compromises or actual losses in pilot motion cues. When these are provided by servo-driven cabs, accelerations must be washed out. That is, to avoid unreasonably large simulator cockpit cab motions, only acceleration on sets can be represented. Sustained accelerations must be tapered off smoothly and quickly in the ground-based systems, or they must be simulated by pressures applied to the pilot’s bodies with servo-controlled pressure suits. Belsley provided an early summary paper in this area. Later on, Ashkenas and Barnes reviewed the utility and fidelity of ground-based simulators in flying qualities work.

 There is a debatable size problem involved with the use of variable-stability airplanes. W. H. Phillips points out that in Robert Gilruth’s original handling qualities studies, contrary to the expectations of many people, pilots were satisfied with much lower values of maximum rolling velocity on large airplanes than on small ones. This finding is reflected in the pb/2V criterion of acceptability, which allows half as much maximum rolling velocity when the wing span is doubled at the same airspeed.

 Again, pilots of small airplanes choose lower control forces than do pilots of large airplanes. Phillips concludes that pilots adapt to airplanes of different sizes and that erroneous results may be obtained if this adaptable characteristic of the human pilot is not accounted for. This might be the case when a large airplane is simulated with a much smaller variable-stability airplane, or vice versa.

 A counterargument is that two fundamental airplane dynamics properties affecting airplane feel vary systematically with airplane size, giving the pilot a cue to the size of the airplane, even if all that the pilot sees of the airplane is the cockpit and the forward view out of the windshield. Short-period pitch natural frequency shows a systematic trend downward with increasing airplane weight and size. The roll time constant, the time required for an airplane to attain final rolling velocity after step aileron inputs, shows a systematic trend upward with increasing airplane size.

 Thus, a small variable-stability airplane whose dynamics match those of a large airplane may well feel like the large one to the pilot. W. O. Breuhaus reports that this seems to be the case:

the pilot must be able to convince himself that he is flying the assigned mission in the airplane being simulated...one of the variable-stability B-26’s was used to simulate the roll characteristics of the much larger C-5A before the latter airplane was built. The results of those tests showed a less stringent roll requirement for the C-5A than was being specified for the airplane, and these results were verified when the C-5A flew.

The relative merits of variable-stability air planes as compared with ground-based simulators for representing airplane flying qualities are still being debated; each has its proponents. However, it is a fact that sophisticated ground-based simulators are now absolutely integral to the development of new aircraft types, such as the Northrop B-2 and the Boeing 777. Typically, ground-based simulators handy to the engineering staff are in constant use during airplane design development. At the same time, variable-stability airplanes remain important tools for design validation and for the development of generalized flying qualities requirements.

 The question of when variable-stability airplane simulation is really necessary is taken up by Gawron and Reynolds. They provide a table of ten flight conditions that seem to require in-flight simulation, together with evidence for each condition. An example condition is a high gain task. Evidence for this is the space shuttle approach and landing and other instances such as YF-16 and YF-17 landings.

 The Air Force operates the new VISTA/F-16D variable-stability airplane and the Europeans are running impressive programs of their own. However, in-flight simulation was not considered for the Jaguar fly-by-wire, the EAP, or for the Eurofighter. Shafer provides a history of variable-stability airplane operations at the NASA Dryden Flight Research Center, with an extensive bibliography.

The V/STOL Case.

Vertical or short takeoff and landing airplane flying qualities requirements present special problems because V/STOL airplane technology covers a large range of possibilities. So far, we have seen tilt rotor, lift fan, vectored thrust, blown flaps, and convertible rotor wing versions. Although the military services have taken up the challenge and in 1970 issued a V/STOL flying qualities specification, MIL-F-83300, there is a danger that the requirements are specific to individual designs, those available for testing at the time.

MIL-F-83300 recognizes three airspeed regimes, from hover to 35 knots, from 35 knots to an airspeed where conventional flying qualities requirements apply, and airspeeds above conventional flying speeds. Requirements are either for small perturbations about some fixed operating point or for accelerated or transitional flight. The V/STOL small-perturbation longitudinal dynamics requirements take the familiar MIL-8785 form of acceptable and unsatisfactory boundaries in terms of real and imaginary parts of the system roots. So do the lateral-directional requirements resemble those for conventional airplanes, as requirements on the shape of the bank angle versus time curve for rolls and on permitted adverse yaw.

The Air Force Wright Laboratory’s VISTA, or multiaxis thrust-vectoring airplane, a variable-stability machine based on the General Dynamics F-16D. Thrust is vectored up to 17 degrees in pitch and yaw, primarily for high-angle-of-attack research.

A complication when applying the familiar period and damping requirements to the roots of V/STOL motions is convergence of the ordinary modes of motion at very low airspeeds. For a powered-lift STOL configuration the longitudinal short-period and phugoid modes merge at an equilibrium weight coefficient, equivalent to the lift coefficient, of 3.5. A similar trend shows up in the lateral case, where a spiral mode approaches in time constant the usually much shorter rolling mode at a large value of the equilibrium weight coefficient.

The problem of establishing V/STOL flying qualities requirements that are not tied to specific configurations was taken up again after MIL-F-83300, for the most part with the help of ground simulations and variable-stability airplanes. In 1973, Samuel J. Craig and Robert K. Heffley used analysis and ground simulation to explore the role of thrust vector inclination during STOL landing approaches.

 Still later, in papers delivered in 1982 and 1983, Roger H. Hoh, David G. Mitchell, and M. B. Tischler looked for flying qualities generalizations in VTOL transitions and STOL path control for landings. Precise pitch attitude control at high bandwidth appears to be critical in transitions because of the sensitivity of vertical rate to pitch attitude. However, the writers found a number of possible requirements for the landing flare control maneuver of STOL airplanes. That series closed out with a major effort to extend the MIL Prime Standard and Handbook concept to STOL Landings.

An area that seems to require more attention is the lift loss in the vortex ring state during increases in descent rate. Vortex rings recirculate the rotor down flow back into the rotor, instead allowing it to descend and produce lift. This is a performance problem for single-rotor helicopters. However, for the tilt-rotor V-22 Osprey, a vortex ring on one of two laterally located rotors is believed to have produced an unrecoverable roll.

The considerable experience gained by DERA and BAE systems in V/STOL projects, leading to the Harrier and the VAAC Harrier, is summarized by Shanks and Fielding. One key finding was that eliminating conscious mode changing provides a large reduction in pilot work load. The V/STOL becomes a “conventional aircraft that can hover.” Another finding was the need to use closed-loop analysis to specify propulsion system characteristics in terms of bandwidth and response linearity.

Pilot-in-the-loop technology has made significant contributions to understanding the special flying qualities requirements of STOL and VTOL airplanes. This approach is especially valuable because it is not closely tied to the design details of specific machines.

Two Famous Airplanes.

NACA measured the flying qualities of the super marine Spitfire VA fighter in 1942 and the Douglas DC-3 transport in 1953, both at the Langley Laboratory. These airplanes had been built in large numbers, had served magnificently in World War II, and had inspired great affection among their pilots. Yet neither of these famous airplanes had the specified level of the most basic stability of them all, static longitudinal stability, as measured by the elevator angles required for steady flight at various airspeeds. This form of stability is often called stick-fixed stability.

The Spitfire shows neutral stick-fixed stability under all flight conditions. The DC-3 is stable only in power-off glides or with cruise power. With normal rated power or in a power approach condition at aft loadings, increasing amounts of down elevator are needed as the air speed is reduced, along with push column forces. For both air planes there are other less striking deviations from NACA and military stability and control specifications. What should be made from all of this?

The Spitfire and DC-3 cases should not furnish an excuse to dismiss flying qualities requirements. It is reasonable to assume that if the Spitfire and DC-3 were longitudinally stable under all flight conditions, both of these fine airplanes would have been even better. In fact, the Spitfire Mark 22, developed at the end of the war, had a 27 percent increase in tail areas and flew “magnificently,” according to one account. The bottom line is that nobody has ever found it feasible to run definitive, statistically valid experiments on the value of good flying qualities in terms of reducing losses in accidents or success in military missions. Instead, we rely on common sense. That is, it is highly plausible that good handling qualities in landing approach conditions will reduce training and operational accidents and that precise, light, effective controls will improve air-to-air combat effectiveness. That plausibility is essentially what energizes the drive for good flying qualities, in spite of apparent inconsistencies, such as for the Spitfire and DC-3.

Changing Military Missions and Flying Qualities Requirements.

Flying qualities requirements for general aviation and civil transport airplanes are predictable in that these airplanes are almost always used as envisioned by their designers. This is not so for military airplanes. The record is full of cases in which unanticipated uses or missions changed flying qualities requirements. Four examples follow.

A4D-1 Skyhawk. The A4D-1, later the A-4, was designed around one large atomic bomb, which was to be carried on the centerline. A really small airplane, the A4D-1 sits high on its landing gear to make room for its A-bomb. The airplane was designed to be carrier-based. However, the A4D-1 was used instead mainly as a U.S. Marine close-support airplane, carrying conventional weapons and operating from single-runway airstrips, often in crosswinds. The vestigial high landing gear meant that crosswinds created large rolling moments about the point of contact of the downwind main tire and the ground. In simpler terms, side winds tried to roll the airplane over while it was landing or taking off. Originally, pilots reported that it was impossible to hold the upwind wing down in crosswinds, even with full ailerons. Upper surface wing spoilers had to be added to the airplane to augment aileron control on the ground.

B-47 Stratojet. This airplane started life as a high-altitude horizontal bomber. It’s very flexible wings were adequate for that mission, but not for its later low-altitude penetration and loft bombing missions. Loft bombing requires pull-ups and rolls at high speed and low altitude. In aileron reversal ailerons act as tabs, applying torsional moments to twist a wing in the direction to produce rolling moments that overpower the rolling moments of the aileron itself. This phenomenon limited the B-47’s allowable airspeed at low altitudes.

 F-4 Phantom. The F-4 was developed originally for the U.S. Navy as a long-range attack airplane, then as a missile-carrying interceptor. A second crew member was added for the latter role, to serve as a radar operator. Good high angle of attack stability and control were not required for these missions, but then the U.S. Air Force pressed the F-4 into service in Vietnam as an air superiority fighter. Belatedly, leading-edge slats were added for better high angle of attack stability and control.

 NC-130B Hercules. This was a prototype C-130 STOL version, fitted with boundary layer control. The airplane’s external wing tanks were replaced by Allison YJ56-A-6 turbojets to supply bleed air for the boundary layer control system. At the reduced operating air speeds made possible by boundary layer control the C-130’s un-augmented lateral-directional dynamics, or Dutch roll oscillations, were degraded to unacceptable levels.

 “Systems engineering” as a discipline was a popular catchphrase in the 1950s. Airplanes and all their accessories and logistics were to be developed to work together as integrated systems, for very specific missions. The well-known designer of naval airplanes Edward H. Heinemann was not impressed. Heinemann’s rebuttal to systems engineering was, “If I build a good air plane, the Navy will find a use for it.” Heinemann’s reaction to systems engineering seems justified by the four cases cited above, in which flying qualities requirements for the airplanes changed well after the designs had been fixed.

Long-Lived Stability and Control Myths.

 The achievements of S. B. Gates, R. R. Gilruth, and others in putting airplane stability and control on a scientific basis have not eliminated a number of early myths attached to the subject. Dr. John C. Gibson lists no fewer than 15 of these myths and counters them with what we know to be correct. A few of the Gibson’s list of 15 myths and corrections follow:

 Wing center of pressure (cp) movement affects longitudinal stability. Correction: Wing center of pressure movement with angle of attack is controlled by the wing’s zero-lift pitching moment coefficient about its aerodynamic center. This parameter affects only trim for rigid air planes. Wing center of pressure has been discarded in modern stability and control calculations and replaced by wing aerodynamic center and zero-lift pitching moment coefficient.

 A down tail load is required for stability. Correction: Stability is provided by the change in tail load with change in airplane angle of attack. The change is independent of the direction of the initial load.

Gibson comments that this myth survives in FAA private pilot examinations and in an exhibit at the National Air and Space Museum in Washington. This subject is distinct from the instability caused by tail down load in the presence of propeller slipstream.

 A stable airplane is less maneuverable than an unstable one. Correction: Unstable airplanes are notoriously difficult to control precisely. Given light control forces, a stable airplane can be pitched rapidly to a precise load factor or aiming point. Gibson says, “...the Hurricane, Typhoon, and Tempest were highly maneuverable and were greatly superior as gun platforms to the skittish Spitfire.”

[carlosebanegas-blog]

“Through the looking glass: envisioning new library technologies”

Drones The word “drone” is the common term for an unmanned aerial vehicle – a robot that combines flight with sensors (usually cameras) to allow for unprecedented freedom in observing and interacting with the world. This column will explore the technology that makes modern drones possible, what makes drones useful and the role of libraries in making drones accessible to their patrons, now and in the future. Common uses for drones Perhaps the best way to understand the potential of drones is to survey some of the most common applications for this technology: 

● The agriculture industry is using drones to monitor and manipulate crops with increasing precision. 

● News agencies use them to take pictures and investigate situations that are too dangerous or expensive for a human reporter. 

● Law enforcement agencies are exploring their capabilities in a number of areas such as monitoring traffic, locating poachers and searching for missing people using thermal cameras.

● Filmmakers are now able to take shots that would have previously required either expensive cranes or helicopters. 

● After disasters, drones can provide a high-level overview of the damaged area and safely explore debris. 

● Drones are being used to create high-resolution images of objects to produce three-dimensional (3D) maps and models. 

Many of these applications are equally appealing to hobbyists and professionals. For some small-scale gardeners, drones can be used to scare away pests, such as deer, or take aerial photographs that provide a new perspective of their garden. For the agriculture industry, drones already account for $864.4 million in spending per year and are expected to grow to account for over $4 billion by 2022, as they are used not only to monitor and plan crops but also to plant seeds and provide accurate pesticide control (Wood, 2016). Although a small flying robot with a sensor is a seemingly simple idea, drones have a tremendous number of potential applications they are posed to break through to become a transformative technology in many areas. In the future, as they become smaller (potentially microscopic), faster and more autonomous (able to make independent decisions and respond dynamically to new situations), they are only going to become more useful and more significant. In this context, it is worth examining the component technologies that make drones possible. Navigation and sensory developments When considering an emerging technology such as drones, it is worth noting that no individual component of the drone is particularly new. The concepts and technology that enable aircraft have been around for a while, as have cameras and other sensory equipment. However, it is only recently that it has become cheap and easy enough for small flying robots to be equipped with sensors of sufficient power that, together, they can create something greater than the sum of their parts. The list of related technologies is much longer, of course. Most modern innovations are dependent on the host of other developments that make up our technological infrastructure. A variety of advances in robotics and aerial design underpin the drones’ flight capabilities. Drones are dependent on computers and wireless technologies for their programming and for communicating. Digital cameras are dependent on cheap storage to be useful. Looking forward, artificial intelligence and advanced sensors will further transform what a single drone is capable of. But ultimately, it is the key combination of the global positioning system (GPS) and inertial-measurement unit (IMU) devices that provide the orientation and location information that enables the drone to maneuver through space, and the sensors that make that navigation meaningful to its human pilot that define drones. GPS units, like drones, were first developed by the military and the underlying infrastructure is still maintained by the US Government. Anyone with a GPS receiver can now access a network of satellites to receive near-instantaneous location and time information. Widespread access to this technology was not available until recently, and when the first commercial GPS unit was sold in the late (able to make independent decisions and respond dynamically to new situations), they are only going to become more useful and more significant. In this context, it is worth examining the component technologies that make drones possible. 

Navigation and sensory developments 

When considering an emerging technology such as drones, it is worth noting that no individual component of the drone is particularly new. The concepts and technology that enable aircraft have been around for a while, as have cameras and other sensory equipment. However, it is only recently that it has become cheap and easy enough for small flying robots to be equipped with sensors of sufficient power that, together, they can create something greater than the sum of their parts. The list of related technologies is much longer, of course. Most modern innovations are dependent on the host of other developments that make up our technological infrastructure. A variety of advances in robotics and aerial design underpin the drones’ flight capabilities. Drones are dependent on computers and wireless technologies for their programming and for communicating. Digital cameras are dependent on cheap storage to be useful. Looking forward, artificial intelligence and advanced sensors will further transform what a single drone is capable of. But ultimately, it is the key combination of the global positioning system (GPS) and inertial-measurement unit (IMU) devices that provide the orientation and location information that enables the drone to maneuver through space, and the sensors that make that navigation meaningful to its human pilot that define drones. GPS units, like drones, were first developed by the military and the underlying infrastructure is still maintained by the US Government. Anyone with a GPS receiver can now access a network of satellites to receive near-instantaneous location and time information. Widespread access to this technology was not available until recently, and when the first commercial GPS unit was sold in the late 1980s, it weighed 1.5 pounds and cost $3,000 (Wolpin, 2014). It was not until the year 2000 that the Department of Defense stopped purposefully interfering with GPS signals, which improved the accuracy of this technology overnight (Sullivan, 2012). IMU devices are less well-known than GPS units, but equally important for ensuring that drones can successfully and easily navigate. They use a combination of accelerometers and gyroscopes to measure the drone’s movement, orientation and acceleration, which are crucial for unmanned flight. Similar to GPS units, this technology was, until recently, prohibitively expensive and cumbersome, but now can be easily and cheaply integrated with GPS units to function as key components of drones’ internal navigation systems. Depending on their application, drones can use a wide variety of sensory tools, such as digital cameras and other sensory inputs. They can collect temperature information, detect infrared light, measure pressure fluctuations and so on – any sensor that can be made portable can be attached to a drone. But the most common device so far has been the camera. Unlike audio information, visual data are relatively easy to collect without being distorted by the movement of the drone itself, and the data are instantly understandable and engaging for most people. Comparatively light, high-quality cameras capable of taking (and storing) images in a wide variety of situations have become progressively cheap and ubiquitous. This has made it possible to create drones that are easy to use, and, more importantly, create drones that have applications that many people can easily understand. 

“Dull, dirty or dangerous” and beyond.

Drones have their history in military applications. They were valued because they enabled robots to complete jobs that were too dull, dirty or dangerous for humans to accomplish. Should a documentary filmmaker use a drone to attempt a dangerous shot of an active volcano? Should an activist organization use a drone to spy on a company they suspect of ethical violations? Should individuals use drones to monitor the perimeter of their homes? Few people want to spend their time continuously monitoring an agricultural field on the off-chance they observe something new about the crop health. If such people could be found, it would be expensive to pay them for their time. Yet a sufficiently inexpensive drone can circle the crop endlessly, alerting humans when it detects something out of the ordinary. Additionally, drones can be sent into situations that would be hazardous for humans. These hazards can be something as benign as agricultural chemicals, or something more dangerous, such as battlefields. As drones have developed, they have moved beyond the simple “dull, dirty or dangerous” duties. Increasingly, they have been able to take on tasks that leverage their unique capabilities. Due to their shape, and the fact that they can fly, they can easily travel to places that are inaccessible to humans. They are also capable of carrying cameras and other specific sensory equipment that have capacities no unassisted human possesses.

Cost 

Undoubtedly, it is the development of a host of technologies that has enabled drones to become mainstream technology. But, as much as the advance in technology has been essential, so too has been the reduction in the cost of that technology. Financially, as the drone becomes cheaper, both to build and to maintain, it can be used in more situations. For example, in risky situations – such as sending a drone into a dangerous area from which it may not return – the potential downside is reduced when the drone is cheaper. But this is equally true when considering “dull” applications, such as monitoring crops. In each case, the value the drones bring must be weighed against the cost of the drone. There are ethical dimensions to these questions, but there are practical ones, as well. When drones were expensive, they had to be developed by the military, where questions of life and death are customary. Now that drones are inexpensive, the stakes are lower, and the potential uses are exponentially more numerous. As the technology continues to develop, this trend is likely to continue. 

Drones in libraries 

Libraries are already beginning to engage with drones to benefit their patrons. At the most basic level, libraries can offer relevant information about drones to help support patrons who are interested in this technology. A library’s offerings can be tailored to meet the needs of a given library’s target population. The support at an agricultural library may be considerably different than at an art library, or a public library. Even public libraries might focus on different sub-populations, using drones to attract teenagers or focus on engaging adult hobbyists. The underlying technology is the same, but the applications and relevant challenges can differ significantly as libraries develop the resources necessary to help their patrons determine how the technology can be useful to them. For almost all drone users, one common issue is local regulations. For instance, in the USA, the Federal Aviation Agency recently released new regulations about drones, including new definitions for what counts as a “commercial” versus a “recreational” drone. As these definitions are dependent upon the weight of the drone, the interpretation of “commercial” comprises many drones that might otherwise be assumed (and even marketed) as recreational. Additionally, under the new rules, all drones need to be registered, even if they are being used exclusively on personal property (Harris, 2015). Around the world, governments are developing regulations to deal with the complex set of issues raised by drones. More and more, technology that is aimed at a general consumer audience has the capacity to violate privacy, or otherwise run afoul of regulations. Libraries can play a crucial role in their communities simply by providing resources to make relevant regulations understandable. 

Checking out drones 

Already, many libraries are beginning to experiment with providing drones for their patrons to check out. When considering the value of initiating a lending program, it is worth reiterating that drones come with a wide variety of capabilities and price points. Offering drones for check-out invariably provides access to this exciting technology to people who would otherwise be unable to use it, but the question becomes, what does this access enable? In some places, such as the University of South Florida, libraries have been loaning out drones for years. In this case, the library is providing access to mid-range, $1,500 drones that are inexpensive enough to be accessible to a resource-rich library, but are prohibitively expensive for many of their students. They envision students using the technology for activities ranging from multi-media art projects, to researching and mapping out energy use on campus (Imam, 2014). Other libraries are providing more inexpensive drones to give members of the public access to the technology for the first time. After all, as with other technology, the cheaper the device, the more a given library can afford, and the less distressing it is when one is inadvertently damaged. 

Library uses: current 

Even libraries that cannot offer drones for check-out have found ways to expose their patrons to the technology. For example, the public library system in Chattanooga, Tennessee, Library offers a hands-on experience flying inexpensive ($50) drones through an obstacle course (Phillips, 2016). Engaging activities such as these can be designed without ever having to loan a drone. Of course, one of the most exciting applications of drones is content creation. Libraries with robust technology centers will want to find ways not only to provide drones but also to consider how this technology can work in conjunction with their existing offerings. If the library already offers access to a 3D printer, or even photo-editing software, then the images produced by drones can be used by these technologies in ways that may not be immediately obvious to patrons. By creating custom programs, libraries can tailor their offerings to take advantage of a full suite of services. Drones do not have to be used by the public to be useful to libraries. After all, libraries are frequently in the business of creating their own marketing materials to promote services. Drones can be used to take videos of the library’s physical space, making use of angles and types of photography that would otherwise be very difficult or even impossible. For example, the New York Public Library, already an impressive building, can be seen in a whole new light when viewed from a drone after hours (Holzer, 2013).

Library uses: [. . .] and in the future 

Not only can drones deliver sensory equipment easily to new spaces, they can also bring along a wide variety of other objects as well. In 2013, Amazon announced an ambitious plan to use drones to deliver packages. This would enable them to quickly and efficiently move items from their warehouses to people’s homes. Now, regulatory barriers notwithstanding, some experts posit this dream could be a reality in the next five years (Lee, 2016). One of the challenges Amazon faces is that many of their items are large and highly variable in size, which complicates door-to-door delivery. On the other hand, while libraries may check out a wide variety of items, most books come within a fairly standard range of sizes and shapes. It is easy to imagine a future in which a library patron requests a book, and it is delivered hours later by a drone directly to that person’s doorstep. Drones could even be used to return the book. This kind of ease-of-use could revolutionize libraries by making them accessible to whole new populations. If speed is not a priority, drones could also increase accessibility to remote areas, becoming a modern-day bookmobile.

Conclusion 

Drones comprise a number of existing technologies that, when combined, can yield powerful and often unexpected results. Drones are poised to become even more influential as associated technology develops and people find ever-more creative ways to use them. As artificial intelligence develops, drones will be able to interpret the world and make independent decisions, allowing them to navigate obstacles independent of humans. Over time, they will have the potential to become smaller, faster and cheaper. As the internet develops, humans will be able to connect drones to other physical objects in their lives, facilitating their utility even further. All of this innovation comes with a number of challenges that libraries are well-situated to help their patrons overcome. Libraries can offer information on ethical dilemmas relating to privacy – as a technology that facilitates new forms of surveillance becomes prevalent and legal – as governments attempt to balance those concerns with the benefits that drones provide. Finally, libraries can give practical information for operating a drone, or provide access to drones directly. By developing this expertise, not only can libraries serve their patrons but they can also be prepared to use drones themselves.

[carlosebanegas-blog]

Unite 9. Quelle journée !

La mère : Allô Sandra, c'est maman. 

Tu es où ? Je t'attends à la gare, le train est arrivé, mais tu n'es pas là. Je suis très inquiète. Tu vas bien ? 

 Sandra : Oui, je vais bien, maman, ne t'inquiète pas. 

Je suis à Paris, à la gare... J'ai raté mon train ! Désolée, je n'ai pas eu le temps de t'appeler, j'ai eu des soucis toute la journée ! 

Pff... je n’ai pas pu voir Luc...Quel dommage... 

 Bon, ce n’est pas grave, mais la prochaine fois tu me préviens ! 

Qu'est-ce qui s'est passé ? Raconte-moi... 

 D'abord, je suis sortie pour prendre le métro, mais c'était la grève ! Alors j'ai pris un vélo. 

Ensuite, je suis arrivée au parc, et là, je me suis perdue... 

C'est un grand parc ! 

Je n'ai pas trouvé le restaurant pour le déjeuner avec Luc. 

 Oh, c'est dommage ! 

Et finalement, vous vous êtes retrouvés ? 

 Non. Je l'ai appelé, mais il ne répond pas au téléphone, je suis étonnée. C'est bizarre. 

 Oh là là ! ma pauvre, tu n'as vraiment pas de chance ! Quelle journée ! 

 Et je dois trouver un billet pour le prochain train, ça me stresse ! Quelle galère !

 C’est raté !

 Chère Sandra, Je suis désolé ! 

J'ai oublié notre rendez-vous d'hier midi au parc ! 

Je ne l'ai pas écrit sur mon agenda. 

D'abord, je me suis souvenu du rendez-vous... à 11 h 45 ! 

Ensuite, j'ai pris un taxi (tu sais, il y avait une grève de métro) mais ce n'était pas une bonne idée. 

Il y avait des embouteillages partout ! 

Finalement, je suis arrivé en retard pour notre déjeuner au parc. 

Ça m'énerve ! Pourquoi je ne t'ai pas téléphoné ? Parce que j'ai perdu mon téléphone ! 

Je suis un peu triste : tu me manques, et on ne s'est pas vus ! 

Et toi, comment ça va ? 

Tu t'es amusée à Paris ? 

Tu es rentrée à Nantes ? Bises, Luc

 Pour exprimer une émotion négative.

Je suis triste, inquiet, inquiète, étonné(e)... 

Quel dommage ! 

Ça me stresse ! 

Ça m'énerve ! 

J'ai des soucis.

 Pour se plaindre/plaindre quelqu'un.

Mon pauvre ! / Ma pauvre ! 

Tu n'as (vraiment) pas de chance ! 

Quelle journée ! 

Quel dommage !

C'est dommage ! 

Quelle galère !

 Pour donner une explication.

Pourquoi tu n'es pas venu ? 

Parce que j'ai oublié le rendez-vous !

 Panne de voiture, quelles sont les règles? 

 Votre voiture est en panne ? 

Vous devez vous arrêter sur la route ?

Pas de panique ! 

Il y a quelques règles de sécurité à connaître.. 

 Votre voiture ne doit pas rester sur la route ! 

Vous devez vous arrêter sur le côté et allumer les feux de détresse. 

 Il faut toujours avoir le gilet jaune et le triangle de sécurité dans la voiture :

le conducteur doit mettre le gilet     jaune avant de sortir de la voiture.

ensuite, il faut poser le triangle     à 30 mètres de la voiture. 

Sur l'autoroute, faites très attention ! 

C'est un lieu dangereux. 

 Il ne faut pas rester dans la voiture. 

Le conducteur et les passagers doivent sortir du véhicule et se mettre derrière les barrières de sécurité. 

 Ne sortez pas de la voiture par la gauche. 

Utilisez les portes de droite. 

 Vous ne devez pas réparer vous-même votre voiture: 

il faut appeler un dépanneur. 

Pour cela, utilisez les téléphones orange placés sur le côté droit de la route. 

 Je n'ai pas de chance, je dois trouver un billet pour le prochain train.

Ne sortez pas de la voiture par la gauche et mettez votre gilet jaune. 

il y a eu un embouteillage et je suis arrivée en retard pour notre déjeuner. 

 Tu as acheté un téléphone orange et jaune. Il n'est pas très joli ! 

Mon chien est jeune et méchant, il a mangé mes chaussures. 

Aujourd'hui, je n'ai pas eu de chance, quelle journée ! C'est dommage, je n'ai pas noté notre déjeuner dans mon agenda !

 Je n'ai pas de chance ! 

 Jérémy : Oh non, le méchant chat ! 

- Bonjour ! Non, je ne me suis pas brossé les dents. 

Et oui, mon chat a fait pipi dans mes chaussures... Bonne journée à vous ! Non ! Non ! 

Pas la panne ! Pas aujourd'hui ! Vite ! le métro ! 

Je vais prendre le métro ! 

Je vais prendre le métro ! J'ai raté le métro. 

Et je suis en retard. 5 minutes, c'est trop long ! Maintenant, il faut courir Aïe ! Ouille, ouille !

Oh ! là, là ! Je me suis fait mal... Pourquoi je ne suis pas resté au lit, moi... ?

 Les superstitions en France

  En France, pour avoir de la chance, on cherche des objets spéciaux : ce sont des porte-bonheur. 

Je me promène à la campagne et je trouve un trèfle à quatre feuilles ? 

Je le garde ! Une coccinelle vient se poser sur moi ? Je la laisse tranquille ! Dans certaines maisons, on accroche un fer à cheval au-dessus de la porte. Vous rencontrez un marin sur le port ? Vous pouvez toucher le pompon rouge de son béret : ça peut porter chance. Enfin, la nuit, regardez le ciel, et cherchez une étoile filante pour faire un vœu et réaliser vos rêves. Et bien sûr, le jour d'un examen, croisez les doigts... et bonne chance ! Mais il ne faut pas être treize à table, mettre le pain à l'envers sur la table, passer sous une échelle ou croiser un chat noir. beaucoup de Français, ces situations portent malheur. Et vous, vous croyez à ces superstitions ?

 Un appel au SAMU

 Le médecin-régulateur : Oui allô ? 

Le standardiste : Oui, Alain, c'est John, je te passe monsieur X, c'est la fiche 166, c'est un monsieur de 27 ans qui a de la fièvre et qui a mal à la gorge depuis deux jours. Tu vas l'avoir en ligne. 

Le médecin-régulateur : D'accord ! Allô, monsieur X ? Bonjour, voilà, c'est le médecin du centre 15. Donc vous avez 27 ans, qu'est-ce qui vous arrive, monsieur ?

Le malade : Bonjour, docteur. Voilà, j'ai mal à la gorge et à la tête. Et j'ai de la fièvre. 

D'accord. Vous avez mal au dos, aussi ?

Oui, j'ai mal au dos, aux bras, et aux jambes. 

Hmm... Vous pouvez vous lever ?��

Non, docteur ! Je suis malade, je suis au lit. 

Qui peut aller à la pharmacie pour vous ? des voisins, peut-être ? Vous pouvez leur demander. 

Je vais demander à ma femme. Je lui envoie un message. Il faut quels médicaments, docteur ? 

Alors, dites-moi votre poids et votre taille, s'il vous plaît. 

Vous pesez combien ? Vous mesurez combien ?

Je pèse 82 kilos, et je mesure 1,75 mètre. 

Alors, il faut de l'aspirine 500. 

Vous prenez trois comprimés par jour pendant trois jours. 

Si ça continue, vous appelez votre médecin et vous lui expliquez votre problème. 

Le malade : D'accord, merci docteur !

 Pour parler de l'état de santé.

Le médecin. 

Qu'est-ce qui vous arrive ?

Vous pouvez vous lever ?

Vous avez mal où ? 

Vous prenez trois comprimés par jour, pendant trois jours. 

Le malade.

Je suis malade.

Je suis au lit, je ne peux pas me lever.

J'ai mal à la.../au.../aux...

J'ai de la fièvre depuis deux jours.

 Pour demander, pour dire le poids et la taille

Quel est votre poids ? 

Vous pesez combien ? 

Je pèse 73 kilos.

Quelle est votre taille ?

Vous mesurez combien ? 

Je mesure un mètre soixante-douze.

 Dans l’armoire à pharmacie 

 Mon chéri, je suis chez ma mère. 

Je lui ai parlé de ton problème et nous avons regardé dans son armoire à pharmacie. 

Il y a une boîte de pansements, un thermomètre, un tube de pommade pour les muscles, un sirop pour la toux, des comprimés pour dormi... mais pas d'aspirine ! 

Je vais passer à la pharmacie, chez M. et Mme Butel, rue de la République. 

Je leur achète un tube d'aspirine. M. Butel est très gentil. 

Je lui explique ton problème et il va peut-être proposer d'autres médicaments. 

À tout à l'heure. Bisou.

 • On utilise les pronoms lui au singulier et leur au pluriel, pour remplacer un complément introduit par à plus personne.

 Je suis chez ma mère. Je lui ai parlé de ton problème.

Je vais passer chez M. et Mme Butel. 

Je leur achète un tube d'aspirine.

M. Butel est très gentil. Je lui explique ton problème.

 J'envoie un message à ma femme.

Je lui envoie un message.

 Vous demandez à vos voisins. 

Vous leur demandez.

 On lui pose des questions. (le professeur) 

On lui parle de ses problèmes de santé. (le médecin) On lui achète des médicaments. (la pharmacienne) 

On lui téléphone pour s'occuper de la voiture en panne. (le dépanneur)

On leur annonce les bonnes et les mauvaises nouvelles. (les amies)

On leur demande de sortir de la voiture. (les passagers)

Je lui raconte ma vie et je lui dis mes secrets. - À ton meilleur ami ?

 Tout va bien !

 Eloïse Pinson : Bonjour, vous êtes sur le répondeur d'Eloïse Pinson; vous pouvez me laisser un message. La grand-mère d'Eloïse : Eloïse, ma chérie, c'est mamie ! Tu es fatiguée ? Tu n'es pas en forme ? Moi, je sais pourquoi ! C'est parce que tu restes en ville ! Il faut sortir de Paris, ma petite fille ! Viens à la maison ! Ici, c'est la campagne. Tu peux prendre quatre ou cinq jours de vacances. Moi, j'ai 75 ans et je suis en pleine forme. Bon... j'ai mal aux yeux, parce que je suis vieille mais tu sais, j'ai marché 8 kilomètres ce matin. Je n'ai pas mal aux pieds, et je me sens très bien ! Bisous.

Vacances de hiver.

 Nous sommes partis en vacances de ski, la semaine dernière. D'abord, il a neigé pendant trois jours, il est tombé plus de trente centimètres de neige ! Le ciel était complètement couvert, il y avait beaucoup de brouillard, donc il était impossible de faire du ski. Nous sommes restés à l'hôtel, ce n'était pas très intéressant, surtout pour les enfants. Heureusement, ils ont joué avec des amis. Il y avait beaucoup de nouvelles familles. C'est vrai qu'il y a un monde fou dans cette station de ski, c'est comme l'année dernière ! Enfin, le ciel s'est dégagé, et il a fait un temps splendide. Nous avons fait autant de ski que possible. Bien sûr, Jérôme a oublié de mettre de la crème solaire, alors il a pris des coups de soleil... Finalement, c'étaient de belles vacances, tout le monde était content et avait bonne mine.

 Devant un cabinet médical.

 Véronique : « Aïe, aïe ! Je ne peux pas manger, j'ai très mal aux dents ! » 

Alex : « Oh, la pauvre ! Moi aussi j'ai un problème... Je ne peux pas marcher parce que j'ai mal au pied.

 Catherine: vous avez mal au nez?!

Pardon, pouvez-vous répéter ? 

J’en entends pas bien car j’ai mal à l'oreille.

 Alex: j’ai mal au pied ! Et je ne peux pas marcher !

Caroline: Silence, s’il vous plaît ! J’ai très mal à la tête.

 Alicia: je connais ce problème, je suis professeur… et puis, je passe beaucoup de temps devant l’ordinateur donc, j’ai mal aux yeux et au cou. 

Aujourd’hui, je dois encore corriger les tests de mes élèves mais j’ai très mal à main.

 Docteur Labosse: Vous avez mal parce que vous n’êtes pas en forme ! Bougez plus ! marchez !

 Jour de grève à Paris.

 Comme tous les matins, les Parisiens se sont levés tôt.

Ils se sont douchés, puis ils ont choisi leurs vêtements et ils se sont habillés.

Ils ont pris leur petit déjeuner et ils ont quitté leur logement.

Mais, quand ils ont voulu prendre le métro, ils ont trouvé toutes les stations fermées !

D'abord, ils se sont énervés, puis ils se sont calmés et ils ont essayé tous les moyens de transports possibles: tramway, bus, rollers, vélo, trottinette.

Ils se sont dépêchés mais ils sont arrivés en retard au travail !

 Les pronoms  compléments d’objet indirect. 

 Je leur donne des informations. 

Je leur annonce le programme. 

aux nouveaux étudiants.

  Je leur indique le chemin. 

Je leur réponds parfois en anglais. 

à des touristes.

 Je lui offre des cadeaux. 

Je lui apporte des fleurs. 

à ma fiancée.

 Je lui chante des chansons. 

Je lui achète des jouets. 

au bébé.

 Je leur écris souvent. 

Je leur téléphone aussi. 

à mes parents.

 Je lui commande une boisson. 

Je lui laisse un pourboire.

au serveur.

 Tu téléphones à tes amis ce soir?

Oui, je leur téléphone après le dîner.

Il écrit à sa mère?

Oui, il lui écrit pour son anniversaire.

Vous parlez à vos enfants? 

Oui, nous leur parlons le plus souvent possible.

Elle sourit à son ami Gustave?

Oui, elle lui sourit tendrement.

Il répond à ses étudiants ? 

Oui, il leur répond clairement.

Tu dis la vérité à tes parents ? 

Oui, je leur dis la vérité, généralement.

Tu t’es souvenu du rendez-vous !

Nous nous sommes perdus dans la ville.

Elles se sont réveillées à 8 heures.

Elle s’est excusée pour son retard.

Je me suis occupé des enfants.

 a. Ils se sont promenés dans le parc et ils se sont bien amusés. b. Ils se sont retrouvés dans un endroit inconnu. Ils se sont perdus. c. Ils se sont excusés pour leur retard.

 Les piétons aussi doivent respecter le code de la route.

Il ne faut pas rester au milieu de la route.

Vous devez traverser sur le passage piéton.

Nous devons marcher sur le trottoir.

Tu ne dois pas jouer au ballon sur la route.

À vélo. Il faut porter un casque.

 Ton vélo neuf est cassé ! C'est pas possible ! 

Il y a la grève ? maintenant ? Et comment je vais rentrer ? 

Tu as oublié notre rendez-vous ? 

J'ai attendu une heure ! 

J'ai perdu mon téléphone. Quel dommage !

 Ce matin, Léa a raté son train.

Il y avait une grève de bus, alors elle a pris sa voiture. Elle est arrivée en retard au travail.

Elle a été stressée toute la journée.

Elle a oublié un rendez-vous. 

Le soir, il y a eu des embouteillages et sa voiture est tombée en panne devant sa maison. Quelle journée !

 Tu ne dois pas courir. 

Il ne faut pas manger. 

Nous ne devons pas prendre de photos. 

Il faut rester assis. 

Vous ne devez pas téléphoner.

 Vous pouvez remplacer le complément par lui ou leur ?

Aïe, j'ai mal à la jambe. On ne peut pas.

Il a parlé à la pharmacienne. Lui.

J'ai acheté un médicament. On ne peut pas.

Nous avons dit bonjour aux infirmières. Leur.

Le docteur propose un sirop à Pierre. Leur.

Il connaît ton médecin. On ne peut pas. 

 Patrick va à la pharmacie et le pharmacien lui conseille une pommade.

 Il faut aller voir le pharmacien et lui demander un sirop.

J'accompagne Stéphanie et Alexandre à l'hôpital, je leur présente le médecin.

Nous connaissons le médecin, nous lui expliquons le problème.

Tu vas voir les infirmières et tu leur demandes une aspirine.

Le médecin conseille un médicament à Alexandre, il lui écrit le nom du médicament.

 Vous posez des questions aux médecins?

Oui, je leur pose des questions. 

 Vous dites à Patrick de venir à l’hôpital ?

Non, je ne lui dis pas de venir à l'hôpital. 

 Vous téléphonez au pharmacien ?

Non, je ne lui téléphone pas.

 Vous annoncez le problème aux parents de Patrick?

Oui, je leur annonce le problème. 

 Vous racontez le problème aux amis de Patrick?

Non, je ne leur raconte pas le problème.

 Il faut partir à l'heure. 

Achète un agenda ! 

Pars en vacances ! 

Il peut prendre une aspirine. 

Vous pouvez prendre votre vélo. 

Il faut appeler un dépanneur.

 Emma téléphone à Lise : elle ne peut pas venir à son rendez-vous. 

Remettez leur dialogue dans l'ordre. 

Emma : A la tête et dans tout le corps. 

Emma : Allô, bonjour, c'est Emma. Excusez-moi, mais je ne peux pas venir. 

Je ne me sens pas bien.

 Emma Je ne sais pas, je n'ai pas de thermomètre. 

Emma : Non, je suis malade, ne viens pas

Emma : Oui, très fatiguée. Je ne peux pas me lever.

��Lise : Moi, j'en ai un. Je peux te l'apporter ? Je peux venir te voir ?

Lise Bonjour Emma ! Qu'est-ce qui t'arrive ? Tu es fatiguée ? 

Lise : Tu as de la fièvre ? i. Lise : Tu ne peux pas bouger ? Ma pauvre ! Tu as mal où ?

 Tu es fatigué, toi ! Je ne me sens pas bien, j'ai très mal à la tête. Va à la pharmacie, achète un médicament.

 Vous avez un médicament pour le mal de tête ? Oui. Mais vous avez un rhume aussi ?

Je ne sais pas, oui. Je voudrais un médicament, s'il vous plaît, je dois travailler. Allez chez le médecin, monsieur ! 

 J'ai mal à la tête et au ventre, j'ai de la fièvre et je dois beaucoup travailler. 

Hum... Il faut rester à la maison et dormir.

 Il fait chaud, et il y a des embouteillages ! 

Quelle journée ! Quelle malchance ! 

Tu as la bouche... toute rouge ! 

Un fer à cheval ! De ma région ! 

Jean ! Ne passe pas sous l'échelle ! 

C'est mon chat, il est noir mais il est gentil.

 Willy a marché sous la pluie sans manteau et sans parapluie.

Il a mal à la gorge, aux oreilles et il a le lez rouge.

Willy a couru un marathon. Il a mal aux jambes, aux pieds, aux bras: il a mal partout !

 Willy a travaillé très tard sur son ordinateur et il n’a pas dormi. Il a mal aux yeux, au dos et à la tête!

 Regarde tes cheveux ! Ils sont plein de shampoing. 

Vous avez déjà eu un chien ? 

Aujourd'hui, je vais en manger pour la première fois.

Il a un objet qui porte chance ?

Oui, un tee-shirt porte-bonheur jaune.

Ta jambe fait encore mal ? Change de médecin !

 Le docteur mange avec nous ? ou avec une amie ? b. Madame, n'oubliez pas votre aspirine. Elle est là ! c. C'est un trèfle à quatre feuilles. d. Il habite au treize avenue de la Chance. e. Notre ami est triste. Je l'invite au restaurant

 Journée difficile... 

 Simon : Bonjour, excuse-moi, je suis vraiment en retard. 

Lucie : Simon, tu as oublié notre rendez- vous ? 

Mais non ! J'ai eu une journée difficile. 

Pourquoi est-ce que tu as eu une journée difficile ? 

Parce que j'ai raté mon train. 

D'abord, cela m'a stressé, ensuite j'ai perdu un dossier dans le train, et je me suis disputé avec un collègue. 

Enfin, j'arrive à 18 h 30 au café et tu es en colère contre moi. 

Quelle galère ! Mon pauvre ! Simon : Ne ris pas, c'est de la malchance ! 

Tu es superstitieux, toi ? Simon : Non, mais... quand je rate mon train, après, tout se passe mal ! C'est toujours comme ça. 

La prochaine fois, reste chez toi Simon : Ah, merci du conseil.

 Vous recevez ce SMS.

Bonjour,

C'est le docteur Lafforgue. J'ai vu votre scanner. Bonne nouvelle : vous n'avez pas besoin d'opération. Mais attention, vous devez continuer à bien prendre vos médicaments matin et soir. C'est très important quand on a mal au ventre comme vous. On se revoit dans 2 semaines pour vérifier que tout va bien. N'oubliez pas d'appeler ma secrétaire. Elle prend les rendez-vous le matin entre 8 h et 12 h. 

Bonne journée. A bientôt ! Dr Lafforgue

Je me suis levé à six heures et demie.

Elle s’est lavée et s’est habillée.

Tu t’es rasé ce matin.

Ils se sont mariés l’année dernière.

 Nous lui avons offert des chocolats.

Elle ne leur a pas parlé de ce voyage.

Tu vas lui téléphoner pour la fête ?

Je leur écris souvent des lettres.

Ce film ne leur plaît pas beaucoup.

[carlosebanegas-blog]

Unité 10. Beau Travail !

FOIRE AUX QUESTIONS.

 Erasmus, qu'est-ce que c'est ? 

C'est un programme de la Commission européenne ouvert à tous. Il encourage la mobilité des jeunes et des professionnels dans les domaines de l'éducation, la formation, la jeunesse et le sport. C'est aussi un programme d'échange pour les étudiants. 

 Qui propose Erasmus ? 

Les établissements d'enseignement supérieur : universités, grandes écoles, instituts d'études politiques, écoles d'art, etc. 

 Est-ce que je peux partir avec Erasmus si je ne suis pas étudiant en Europe ? 

Oui. Erasmus est un programme international d'études. 

Si vous êtes inscrit dans une université partenaire, vous pouvez partir avec Erasmus. 

 On peut faire quels cursus avec Erasmus ? 

De nombreux parcours universitaires sont possibles (diplómes de licence, master, doctorat...) dans les disciplines de votre choix: langues, lettres, droit, économie, physique, mathématiques, médecine, sociologie…

 Où est-ce qu'on peut partir ?

Dans les pays de l'Union européenne (Allemagne, Espagne, France, Grèce, Roumanie, Slovaquie...) et dans les pays partenaires (Albanie, Arménie, Islande, Liban, Russie, Turquie...). 

 Comment partir avec Erasmus ? 

Renseignez-vous sur le site Internet et cherchez votre discipline. 

Quand vous avez trouvé une université d'accueil, préparez votre dossier et surveillez le calendrier:

vous devez déposer votre dossier de candidature complet avec votre CV avant la date limite! 

 Quelles sont les aides financières ? 

Si vous participez au programme Erasmus, vous recevez une bourse de l'Union européenne pour le logement, le voyage et la vie de tous les jours.

 Au fait ! CV est l'abréviation de curriculum vitae. 

On présente ce document à des employeurs quand on cherche du travail.

Ils sont partis avec Erasmus.

 Lucie Je m'appelle Lucie, je suis belge et je suis étudiante en master 1 de sciences politiques, en Suède, à Stockholm. 

L'hiver, il fait très froid, mais c'est une ville merveilleuse. 

Avec Erasmus, je vis une expérience formidable ! 

C'est une occasion unique de découvrir une nouvelle culture, une nouvelle langue et de rencontrer des étudiants de pays différents. 

Maintenant, j'ai envie de m'intéresser aux questions européennes : ça me donne des idées pour la suite, pour ma future vie professionnelle... 

 Livia : Je m'appelle Livia, je suis italienne et j'étudie l'informatique à l'université de Madrid, en Espagne. 

Je suis en 3 année de licence. 

C'est une vraie chance de voyager comme ça à mon âge, c'est très enrichissant. 

La bourse Erasmus me permet de vivre bien, d'avoir un petit logement dans le centre et de sortir de temps en temps. 

Cette expérience m'aide à préciser mon projet professionnel. 

En tout cas, je vais continuer à voyager... et je vais peut-être m'installer dans un pays étranger ! 

 Piotr : Je m'appelle Piotr, je suis russe et je suis inscrit à l'université de Lisbonne, au Portugal. Je suis étudiant en architecture, en M2. 

J'ai beaucoup de chance d'être ici : pour mon avenir professionnel, c'est un avantage de parler une nouvelle langue et de connaître d'autres méthodes de travail.

 Pour décrire une expérience positive.

Je vis une expérience formidable.

C'est un avantage de parler espagnol.

J'ai beaucoup de chance de voyager.

C'est une occasion unique de m'enrichir. 

Cette expérience me permet de progresser. 

 Pour parler de ses études.

Je suis étudiant en master 1 d'économie. 

Je suis en (3e année de) licence. 

J'étudie l'architecture. 

Je suis inscrit à l'université de Lisbonne.

 Découvrons le campus !

Chers étudiants, Bienvenue au campus de l'université Pierre et Marie Curie !

 Notre université existe depuis 1934. 

Elle a longtemps été réservée aux cursus scientifiques. 

Aujourd'hui, elle est toujours renommée, et nous avons le plaisir d'ouvrir un département d'économie. 

L'université Pierre et Marie Curie, c'est :

 5 départements : biologie, informatique, mathématiques, physique-chimie, économie.

4 amphithéâtres pour étudier dans de bonnes conditions. 

Plus de 100 salles de cours. 

Des laboratoires équipés pour accueillir les enseignants-chercheurs.

Une bibliothèque avec plus de 50000 ouvrages et une bibliothèque numérique en ligne. 

2 restaurants universitaires pour faire des repas complets, et une cafétéria. 

5 Un gymnase, un stade et des espaces verts. 

 Pendant la semaine de la rentrée, n’oubliez pas d'aller au secrétariat pour obtenir votre carte d'étudiant, Profitez de votre année ! 

Christine Carambani, présidente de l'université 

 Pour exprimer le but.

J'apprends I'anglais pour le travail. (pour + nom).

Je vais au secrétariat pour obtenir ma carte d'étudiant. (pour + infinitif).

 La condition avec si.

Si vous êtes inscrit dans une université partenaire vous pouvez partir avec Erasmus.

Si vous participez au programme Erasmus, vous recevez une bourse de l’Union européenne.

Si tu es étudiant, tu peux étudier à l’étranger avec Erasmus.

S’il étudie, il peut réussir.

 Il faut bien dormir. Si vous mangez bien.

Il faut bien manger. Si vous mangez bien.

Il faut bien étudier. Si vous étudiez bien.

Si vous participez bien. Si vous vous entraînez.

 Salut Clarissa ! Je suis Nora, nous avons été ensemble pendant deux ans en licence de mathématiques !

Salut Nora, alors, qu’est-ce que tu fais maintenant ?

J’étudie toujours les mathématiques. Et toi?

J’ai étudié l’économie pendant deux ans et j’ai passé un concours pour être professeur.

Ah! J’ai pensé longtemps à passer un concours. Mais pendant mon master, j’ai découvert le métier de chercheur.

Tu prépares toujours un diplôme ?

Oui, un doctorat.

 J'ai étudié à Leipzig pendant deux ans. 

Sam étudie toujours la philosophie. 

Lya et Laure ont longtemps étudié à la bibliothèque. 

Luc a travaillé dans un restaurant pendant ses études. 

Nous ne cherchons pas de travail : nous sommes toujours étudiants. 

Vous avez voyagé pendant votre année d'études en Italie.

 Marianne. Licence de droit. 

Objectif: devenir avocate.

Elle est en licence de droit. 

Elle étudie pour devenir avocate.

 Jonas est inscrit à l'université Jean Jaurès. 

Il étudie pour le plaisir d'apprendre. 

 Lola est en master de chimie. 

Elle étudie pour travailler en laboratoire. 

 Soraya est inscrite à l'université du Québec à Laval. 

Elle étudie pour faire de la recherche. 

 Bacary étudie le chinois pour pour son travail.

 Bonjour, je viens pour m’inscrire.

Bonjour ! Vous voulez préparer quel diplôme ?

Un masters

Dans quelle discipline ?

En sociologie.

Alors, je vous donne le dossier. Vous devez le remplir et le remettre au secrétariat de sciences sociales 

Et quand est-ce que j’ai listé des professeurs ?

Après l’inscription administrative.

 Où est-ce que je peux déjeuner le midi?

Tu peux déjeuner le midi au restaurant universitaire.

 Où est-ce que je peux trouver des livres?

 Tu peux trouver des livres à la bibliothèque. 

 Amélie étudie les langues, où est-ce que je peux la retrouver ?

Tu peux trouver Amélie au département de langues étrangères.

 Où est-ce que je peux faire du sport?

Tu peux faire du sport au gymnase. 

 Quelle est la salle de cours a coûté du secrétariat ?

La salle de cours à côté du secrétariat est l'amphithéâtre.

 Université 2.0.

 Le FacLab de l'université de Cergy-Pontoise est un lieu ouvert à tous : il réunit des étudiants, des chercheurs, des enseignants, des designers, des artistes, des ingénieurs…

 Créer.

Vous avez une idée d'objet et vous voulez le créer ? Le FacLab met à votre disposition les machines nécessaires à la réalisation de votre projet : imprimante 3D, outils de découpe (bois, tissu, etc.), machine à coudre... Des techniciens et des enseignants sont là pour vous accompagner.

 Partager.

Ici, on apprend à plusieurs ! 

Les utilisateurs expérimentés partagent leurs connaissances. 

Les plans de fabrication des objets sont accessibles en ligne à tous les utilisateurs de fablabs partout dans le monde.

 Apprendre.

Dans le FacLab, vous prenez part aux projets de fabrication des autres membres. Vous pouvez aussi participer à des ateliers, à des formations…

 « fablab », qu'est-ce que c'est ?

Les fablabs (« laboratoires de fabrication ») sont nés à la fin des années 1990 au Massachusetts Institute of Technology (MIT), aux États-Unis. Aujourd'hui, il existe de nombreux fablabs dans le monde, notamment dans plusieurs universités françaises (Bordeaux, Le Havre...) et francophones (Lausanne, Laval, Rabat, Tunis...).

 On, le cliché ! 

« Le système éducatif français est un des meilleurs du monde. » 

D'après le classement du Times Higher Education, l'École normale supérieure de Paris (54º) est la seule parmi les 100 meilleures universités dans le monde en 2015. L'année précédente, il y avait deux universités françaises dans ce classement.

 Francophonie.

L'Agence universitaire de la Francophonie est une association pour développer l'enseignement supérieur en français. Elle propose aussi aux étudiants des bourses de mobilité et des cursus en ligne (FOAD, MOOC)...

 Avant, j’étais très timide.

Pour guérir ma timidité, j’ai suivi un stage et j’ai appris à être sûr de moi.

 Avant, il ne savait pas danser. 

La danse ? Il s'est inscrit à un cours.

Maintenant, il danse parfaitement.

 Avant, elle n'arrivaient pas à s’endormir.

Pour dormir plus facilement. 

Elle a arrêté de boire du café.

Maintenant, elle dort au moins huit heures par nuit.

 Il y a dix ans, je pesais 96 kilos. 

Pour perdre des kilos, j’ai fait un régime strict: j’ai supprimé l’alcool, les bonbons et les pâtisseries.

Aujourd’hui, je ne fais que 65 kilos.

 Avant, nous habitons un studio sinistre.

Dans notre studio: nous avons repeint les murs blanc, nous avons changé la moquette et nous avons mis des posters aux couleurs vives sur les murs.

Aujourd’hui, nous nous sentons bien chez nous.

 Avant, je vivais seul. 

Plus connaître de nouveaux amis, j’ai décidé de m’inscrire dans un club de natation et de randonnées.

Maintenant, je connais plein de monde et j’ai de nombreux amis.

 IL A RENCONTRÉ SA FEMME À L'ALLIANCE FRANÇAISE PARIS ILE-DE-FRANCE.

 Je m'appelle Matthew. Je suis arrivé à Paris à 24 ans pour mon travail. Avant, je vivais en Angleterre et je ne parlais pas français. Je me suis inscrit dans une école de langue française à Paris pour faciliter ma vie quotidienne et professionnelle. Au début de mon apprentissage, j'ai rencontré des gens de différentes nationalités et j'ai fait la connaissance de Cindy, une jeune femme américaine de 25 ans. Nous étions tous les deux débutants et nous nous aidions quand nous avions des difficultés. Nous avons fait des progrès en français et, aujourd'hui, nous travaillons tous les deux en France. Nous sommes mariés depuis trois ans.

 L'histoire de Martina (situation initiale, événements importants, situation actuelle). 

 Il y a 5 ans, j'habitais à Zagreb. J'étais étudiante. Je n'avais pas d'enfant. Je sortais beaucoup.

Puis, j'ai fini mes études. J'ai déménagé à Paris. J'ai trouvé un travail de professeur à l'université. J'ai eu un enfant.

Aujourd'hui, j'habite et je travaille à Paris, je gagne plus d'argent qu'avant mais je sors moins qu'avant. Je suis très occupée par ma vie professionnelle et ma vie familiale.

 Prof de FLE en Thaïlande Blog prof info.

Il y a 20 ans, j'ai réussi un master de FLE. Après mon master, je suis parti en Thaïlande et j'ai travaillé comme professeur de français. J'étais heureux : mon travail était intéressant et les étudiants m'aimaient beaucoup. Et puis, j'ai rencontré ma femme et nous avons eu un enfant. Nous avons décidé de rentrer en France. Maintenant, je travaille à Marseille.

 Rosalie et Jules.

 Quand Rosalie et Jules étaient jeunes mariés, ils vivaient dans un modeste appartement à Dunkerque, dans le Nord de la France. À l'époque, Jules était comptable dans une entreprise de plomberie et Rosalie était secrétaire dans un cabinet d'assurances. Ils n'avaient pas encore d'enfant, donc ils pouvaient partir en vacances assez librement. Le problème, c'est qu'ils n'avaient pas beaucoup d'argent. Comme ils aimaient beaucoup la campagne et le climat agréable du Sud-Ouest, ils s'installaient tous les ans dans un village du Périgord. Un fermier leur louait une petite chambre pendant deux semaines et ils passaient leurs journées à marcher, à pique-niquer et à rêver à leur futur château dans cette magnifique région. Ensuite, leur vie a changé. Ils ont eu trois enfants, Jules a ouvert son propre cabinet comptable, Rosalie est devenue assistante de direction. Quelques années plus tard, ils ont acheté une vieille maison dans le Périgord, à quelques kilomètres de Sarlat. Ils ont passé des années à la rénover eux-mêmes. Maintenant, ce n'est pas un château, mais c'est une très jolie maison, chaleureuse et couverte de fleurs, où toute la famille passe des vacances heureuses.

 Nelly.

Avant, j’avais beaucoup de difficultés en cours d’allemand, je ne comprenais pas tout et je ne trouvais pas vraiment d’intérêt à apprendre une langue étrangère. Puis, j’ai participé à un échange.

Je suis allée dans une famille allemande pendant deux semaines et j’ai fait beaucoup de progrès.

Aujourd’hui, je peux écrire des méls en allemand à mon amie allemand et parfois je lui téléphone.

 Avant, c'était une plage tranquille. Il y avait très peu de baigneurs. On trouvait toujours de la place. 

Puis le tourisme s'est développé. Des hôtels et des restaurants se sont installés. Maintenant, la plage est très fréquentée. On peut à peine s'asseoir. L'endroit est devenu une station balnéaire. 

 Il y a quelques années, Stéphane était célibataire. Il vivait seul et n'était pas très heureux. Il trouvait la vie triste, il se sentait seul. Un jour, il a rencontré Marianne et est tombé amoureux. Après quelques années de vie commune, ils se sont mariés. Ils ont eu un enfant, puis deux, puis trois. Stéphane est maintenant un père heureux et un mari comblé.

 Je voudrais partir en Turquie pour commencer un cursus de littérature et devenir professeure. 

 Mon frère est pâtissier mais il voudrait découvrir un nouveau métier : pourquoi pas boucher ? 

Je reçois une aide financière pour étudier à l'étranger. 

Quand ma bourse arrive, je coche le jour sur mon calendrier.

 Mon parcours professionnel.

 Dialogue 1.

 L'avocate : Bonjour... Justin ? C'est ça ? 

Justin : Oui c'est ça. Bonjour madame. 

Vous êtes étudiant ? 

Oui. Je suis en 3° année de licence de droit. 

Mais je n'ai pas choisi ma spécialité. 

C'est important pour votre future carrière. 

Qu'est-ce que vous avez envie de faire comme métier ? J

Je rêve d'être avocat... Mais ce n'est pas facile. Vous êtes avocate ? 

Oui. C'est vrai, les études sont sélectives, et vous devez passer un concours qui est difficile. 

Ensuite, on travaille beaucoup, on étudie longtemps les dossiers, on fait beaucoup de recherches... 

Parfois, le week-end, je prépare les dossiers qui sont urgents. 

Il n'y a pas d'horaires fixes. 

Est-ce que c'est un métier stressant ? 

Un peu oui, parce qu'on a des responsabilités importantes. 

Et puis aussi parce qu'au tribunal, il faut parler en public pendant le procès. 

Mais c'est un métier magnifique ! 

C'est important de permettre aux gens de se défendre. 

On est là pour eux, pour leur donner une voix. 

C'est un très beau projet professionnel !

Oh oui, c'est sûr : je veux être avocat. Je suis motivé !... 

Merci, madame. Bonne journée. 

 Dialogue 2.

Audrey : Bonjour, monsieur. 

Le jardinier : Bonjour ! Comment vous vous appelez ? 

Audrey. Je suis étudiante et je ne sais pas quel métier je veux faire... 

J'espère que je vais trouver des idées ici. 

Je vois... Qu'est-ce que vous étudiez ? 

Je suis en L1 de biologie. Et aussi... je sais dessiner. 

Je prends des cours de dessin en dehors de l'université, c'est ma passion. 

J'aime beaucoup dessiner des fleurs. 

Donc, vous vous intéressez aux plantes ? 

Ah oui ! Chez mes parents, il y a un petit jardin. 

Je connais bien les fleurs. Je suis douée pour ça, il paraît ! 

Vous avez pensé à être jardinière ? 

Jardinière ? 

Oui : dans les parcs, les châteaux, ou chez des gens... Ça vous plairait ? 

Moi, c'est mon métier. 

Vous pouvez m'en dire plus ? 

Eh bien, c'est un métier qui est très varié : je dois bien connaître les fleurs que je plante mais il faut aussi être un peu artiste, avoir de l'imagination pour faire un beau jardin... Audrey : Et quelles sont les conditions de travail ? Vous travaillez dehors ? 

Oui, on est tout le temps à l'extérieur, été comme hiver. 

Mais j'ai beaucoup de liberté pour m'organiser : je choisis les commandes que je préfère et les horaires qui me conviennent... et je n'ai pas de chef ! 

C'est une super idée ! 

Merci du conseil !

 Pour exprimer une capacité, une compétence. 

Je sais dessiner. 

Je peux porter des objets lourds.

Je connais (bien) les fleurs.

Je suis doué(e) pour la peinture/peindre.

 Pour exprimer un souhait ou un projet professionnel.

J'espère que je vais réussir. 

J'ai envie de défendre les gens. 

Je rêve d'être architecte. 

Ça me plairait (de travailler dehors). 

Je suis motivé(e) (pour passer le concours). 

C'est mon projet professionnel.

 Les pronoms relatifs « qui » et « que ».

 Vous devez passer un concours qui est difficile.

Le week-end, je prépare les dossiers qui sont urgents. Je dois bien connaître les fleurs que je plante.

Je choisis les commandes que je préfère et les horaires qui me conviennent.

Vous faites des études. Ces études sont difficiles.

Vous faites des études qui sont difficiles.

Je connais un avocat qui est excellent.

Jeanne travaille dans un quartier que j'adore.

C'est un travail qu'il aime.

Je fais un métier que j'aime.

J’aime parler avec des professionnels qui connaissent leur métier.

Le diplôme que je prépare permet d’être dentiste.

J’ai des horaires de travail qui sont pratiqués.

Les commandes qu’il reçoit sont très intéressantes.

 Le médicine est un cursus qui est long.

Martin a le diplôme qui est nécessaire à son inscription en master.

C’est le dossier que je t’ai envoyé hier.

Voici le professeur qu’ Armelle adore.

Jean Nouvel est le secrétaire qui m’a aidé à m’inscrire.

Prends le livre que je t’ai donné.

J’ai choisi un cursus qui est court.

Je te présente Francisco que j’ai rencontré à la fac.

Elle suit des cours qui ont lieu le matin.

L’informatique est une spécialité qui est très demandée.

Quelles sont les matières que tu préfères ?

 Je suis motivé par le droit du travail. 

Je sais travailler en équipe. 

J'ai envie d'apprendre de nouvelles choses. 

Je connais bien les logiciels de comptabilité. 

Je suis doué pour m'organiser. 

Je peux faire un budget. 

Ça me plairait de travailler dans un cabinet d'avocats.

 Mon parcours.

 Il y a 6 ans, j'habitais à Honduras. Je venais de terminer mon échange d'un an en Autriche.

J'étais au lycée. Là-bas, je vivais dans une famille autrichienne et appris à parler allemand.

Puis, j'ai fini mes études au lycée et j'ai reçu une aide financière pour étudier à l'étranger.

J'ai déménagé à Taiwan et j'ai commencé mes études d'ingénieur en aérospatiale.

J'y ai vécu pendant cinq ans et j'ai appris la langue très bien.

J'ai obtenu mon diplôme en 2019 et je suis ensuite revenu dans Honduras et j'ai commencé mon stage dans l'aviation civile.

Aujourd’hui, j'étudie le management de l'aérospatiale à Toulouse Business School et j'apprends aussi le français dans l'alliance française.

 Si tu être un auteur de BD, tu peux apprendre à dessiner.

Si tu travailler le week-end, tu peux être cuisiner.

Si tu être cuisiner,  tu peux travailler le week-end.

[carlosebanegas-blog]

Unite 11. Au grand Air

Ville ou campagne ? 

 Le journaliste : Bonjour à tous, bienvenue dans notre émission Envies d'ailleurs. Aujourd'hui, la parole est aux citadins. Bonjour, Marie. Vous habitez à Paris ?

Marie : Oui.

Pourquoi vous voulez partir à la campagne ?

Parce que j'en ai marre de la ville ! Ma vie ici...

Pffff... C'est trop déprimant ! Je travaille tout le temps. Je veux m'installer à la campagne pour avoir plus de temps libre et profiter de beaux paysages.

Et pour la météo, aussi... C'est trop triste ici, j'en ai assez, je veux du soleil !

: Ah oui, c'est bien connu, on a plus de soleil à la campagne !

Oui, c'est plus agréable. Et puis en ville, c'est trop cher.

Vous avez vu le prix des loyers ?

Ils sont plus élevés dans les grandes villes ! Et les logements sont minuscules. Ça aussi, c'est une raison de partir.

 Bonjour, Karim. Vous aussi vous rêvez de partir à la campagne.

Karim : Oui ! Je me sens mal ici. La pollution, les voitures, je n'en peux plus ! C'est trop stressant.

À la campagne, il y a plus de transports en commun qu'en ville ?

Non, mais on passe moins de temps dans la voiture et dans les bouchons. Et ça, c'est reposant.

 Bonjour, Paul. Toi aussi tu veux aller vivre à la campagne ?

Paul : Oui.

Le journaliste : Pourquoi ?

La ville, c'est pas mon truc. Ici, on habite dans un appartement.

À la campagne, on peut avoir une maison. Et puis, j'aime les animaux et les jeux.

Le journaliste : Il y a plus de jeux à la campagne ?

À la campagne, on peut jouer dehors, dans le jardin. C'est mieux, c'est plus calme qu'en ville.

Le retour à la terre.

Un jour, Mariette et moi on en a eu marre de la ville.

Alors on a loué un camion pour mettre nos cartons et on est partis vivre aux Ravenelles.

Les Ravenelles, c’est chouette, c’est la campagne et il y a des arbres, des fleurs, et des oiseaux.

À l’arrivée, nous attendait Monsieur Henri.

il nous a gentiment tendu les clefs. 

Pour exprimer son insatisfaction.

Ce n'est pas mon truc. 

Je me sens mal, triste…

C'est trop déprimant, stressant.

J'en ai marre / J'en ai assez de la ville ! 

Ça suffit ! Je n'en peux plus !

 Les grandes villes sont plus polluées que les petites villes. 

La campagne, c'est moins déprimant que la ville. 

Les grandes villes proposent plus de loisirs. 

En ville, on passe plus de temps dans les transports en commun. 

À la campagne, les logements sont moins chers qu'en ville.

 Salomé profite moins de la nature que Jules. 

Baptiste est moins stressé par la ville que Margot. 

La vie de Théo est plus calme que la vie de Ninon. 

Jeanne prend plus les transports en commun que Léa. 

Louis est plus proche de la nature que Lily.

 Antoine est un citadin, il habite dans le centre-ville d'Amiens, dans le nord de la France. 

Il vit dans un appartement. Il travaille beaucoup et sa vie est très stressante. 

La grisaille du nord : c'est déprimant ! 

Antoine rêve de quitter la ville et de s'installer dans une maison avec un jardin. 

C'est plus agréable !

 Le sud de la Corse.

 Le sud de la Corse est une région magnifique.

Il y fait très chaud en été et beaucoup de touristes y viennent.

  En hiver, il pleut un peu, il y a moins de touristes et c’est plus tranquille.

 Il y a 3 villes dans cette région: Sartène, dans les montagnes, et Bonifacio et Porto-Vecchio au bord de la mer.

 Bonifacio et Sartène sont deux villes presque aussi petites (environ 3000 et 500 habitants).

 Il y a trois fois plus d’habitants à Porto-Vecchio, mais moins de touristes que dans les deux autres villes, parce qu’il n’y a pas de vieille ville.

 À Bonifacio, on peut visiter la « ville haute » (la vieille ville), avec l’église St. Dominique et le parc de la Carotola et voir un beau panorama.

 À Sartène, il y a un musée de l’histoire ancienne de la Corse, le seul musée de la région, et une très jolie vieille ville. 

 Oui, je m'y intéresse.

Ah non, j’y participe.

Ah non, je n’y participe pas beaucoup

Oui, je m'y intéresse beaucoup, surtout .

Oui, j’y ai participé.

Oui, oui, je m’y suis habitué très facilement.

 Comparer la vie en France et dans votre pays.

 Au Honduras, je vivais avec ma famille à la campagne, à 30 minutes de la ville. 

Souvent, pendant les week-ends, nos amis viennent en voiture de la ville pour rendre visite à mon frère et moi parce qu'ils se sentent très libre au grand air.

Vivre à la campagne, je pense c’est agréable parce que l'air est plus froid et qu'il y a moins de gens et de voitures qu'en ville. Ici, il y a de beaux paysages et les photos en groupe c’est plus belles qu' en ville. 

A Toulouse, je vis dans une grande ville, je prends souvent le métro, et il y a beaucoup de restaurants à choisir. 

A Toulouse, l'air est aussi plus froid que dans la ville du Honduras, et la ville est aussi plus belle que la ville de mon pays. 

 Je veux avoir plus de temps libre.

Les loyers sont plus élevés dans les grandes villes.

A la campagne, il y a plus de transports en commun qu'en ville ?

On passe moins de temps dans la voiture.

A la campagne, il y a plus d'arbres qu'en ville.

 Franck, Céline et leurs enfants.

 Je vis à la montagne, au grand air : je me sens très libre ! Je suis berger depuis dix ans et j'habite avec ma famille dans une ferme. Nous passons nos journées à nous occuper des animaux : moi, je suis avec mes moutons et ma chienne, qui court après les bêtes ! Ma femme Céline est éleveuse de chèvres. On fait du fromage, mais on a aussi des lapins et des poules et on vend les œufs aux habitants du village. Ici, l'hiver, bien sûr, on fait du ski, c'est notre principale activité. L'été, il y a plein de choses à faire. On fait de la randonnée en forêt, on fait du kayak dans les rivières ou bien de l'escalade.

 Maria et Pierre.

Nous, on habite à la campagne. Nos parents sont agriculteurs : ils cultivent des céréales et des légumes dans leurs champs et ils ont des vaches. Vivre à la campagne, c'est génial ! On va à l'école vélo. Et le week- end, on joue au foot avec nos copains, ou alors on joue à des de société la maison. Moi je fais du cheval, mais ma sœur est trop petite ! Parfois, on campe aussi dans la forêt, avec nos parents.

 Karim, Tania et leurs enfants.

 Vivre à la mer, c'est très agréable... On profite de la vie ! Bien sûr, on travaille comme tout le monde. Karim et moi, nous sommes maraîchers. On cultive des légumes et on les vend. L'hiver, on aime bien rester à la maison. Mais à partir du printemps, quand il fait beau, on va tout le temps à la plage et on se baigne... Karim va à la pêche et moi je pratique mon sport favori : je fais de la voile ! L'été, il y a beaucoup de touristes... On préfère se promener sur les petits chemins à la campagne et faire des pique-niques en famille !

 Décrire son mode de vie.

Vivre à la mer, c’est agréable 

Je passe ma journée à m’occuper des animaux.

Ma principale activité, c’est…

L’été, je fais de la voile.

 On vend les œufs aux habitants.

On fait du kayak dans les rivières ou l’escalade.

On joue au foot avec nos copains.

Je fais de la voile.

Nous allons de temps en temps aux marché mais à la maison, nous cuisinons beaucoup avec les produits de jardin.

Je propose des activités aux enfants quand ils rentrent de l’école : nous faisons de la peinture ou nous allons au potager pour jardiner.

Il habite au bord de la mer : tous les week-ends, il fait du bateau avec ses enfants.

L’hiver. A la montagne, on fait du ski et des jeux en famille.

 Le Grand Parc de Miribel-Jonage.

Le grand-père : Voilà, ici c'est le départ du sentier « découverte ». Vous êtes déjà venues ici ? Fanny : Non, pas aussi loin. Mais avec papa et maman, nous sommes déjà venus nous baigner à la base nautique.

Le grand-père : Allez, c'est parti, suivez-moi ! Le grand-père : Nous voici au point 2.

Regardez bien cette forêt... Vous ne remarquez rien ?

Fanny, qu'est-ce que tu en penses ?

Fanny : Euh... Les arbres sont pareils, non ?

La maman : Oui, ils ont la même forme, la même taille... et ils sont alignés en rang !

Tu sais pourquoi, papa ?

Le grand-père : Oui, parce qu'on les a plantés. C'est une forêt artificielle.

Et finalement, cette forêt est aussi grande que douze terrains de football...

La maman : C'est le point 4... quel beau lac !

Le grand-père: C'est un lac artificiel... il a été créé par les hommes.

Et il a le même âge que ta maman !

Fanny : Oh, vous avez vu tous ces oiseaux sur le lac ? Ils sont nombreux... et très différents ! Le grand-père : Oui, au lac des Allivoz, il y a beaucoup d'espèces d'oiseaux aquatiques : des hérons cendrés, des cormorans...

Fanny : C'est quoi un cormoran ?

Le grand-père : Un cormoran, c'est un oiseau noir avec un long cou. Tu vois là-bas ?

Il est aussi bien dans l'air que dans l'eau !

Fanny : Point 6... papi, cette forêt, elle est artificielle ?

Le grand-père: Non Fanny, c'est une forêt naturelle.

Tu vois, les arbres ne sont pas de la même espèce, et ils sont plus rapprochés.

La maman : I fait froid ici... au point 8 !

Le grand-père: Oui, et ce petit ruisseau s'appelle le Rizan.

Fanny : L'eau est aussi claire qu'un miroir !

La maman : Ça y est, nous arrivons au bout du sentier.

Fanny : Oh là là l il y a des champs partout !

Le grand-père : Oui ! Au grand parc de Miribel, il y a environ 400 hectares cultivés !

[carlosebanegas-blog]

eCaravan landed with lower power

Electric propulsion specialist Magnix has confirmed that an electric-powered Cessna 208B Grand Caravan it was demonstrating landed under degraded power after an issue with an inverter during a 2020 test flight. “We had an electrical issue where one of the four inverters did what it was supposed to do – it shut down, leaving the pilot [with] only 75% power,” Magnix chief executive Roei Ganzarski tells FlightGlobal. “It wasn’t that the battery died.” Magnix and flight-testing company AeroTec partnered to fly a Caravan equipped with Magnix’s 750hp (559kW) Magni500 all-electric powerplant. The aircraft, dubbed an “eCaravan”, made its maiden flight on 28 May from Grant County International airport in Moses Lake, Washington. It flew for about 30min before landing safely, according to the company. Ganzarski says the electric system “did exactly what it was supposed to do” during the test flight. The system lost only partial power and the programme has benefited from the lessons learned, he adds. He was responding to a question about whether the aircraft’s pilot had been forced to land without

power. That is only “partially” true, Ganzarski says. “When they had a fault coming out of the electrical system into one of those inverters, that inverter shut down in order not to impact the rest, and did what we call a graceful degradation, leaving the pilot with partial power,” he says. “So, it only shut down a quarter; if you have a fault with an engine, you’d have to shut the whole thing down.” An inverter controls the frequency of power supplied to a motor to control its rotation speed. Economical operation Magnix, with offices in Australia and Seattle, has been working on the Grand Caravan project alongside other electric-aircraft efforts. It is one of two companies supplying propulsion systems for Alice, an all-electric nine-passenger aircraft being developed by sister company Eviation Aircraft. Magnix and AeroTec say their modified Grand Caravan proves that small all-electric aircraft can feasibly and economically operate short routes that airlines had long ago abandoned. Meanwhile, rival electric aircraft developer Ampaire has flown its hybrid-electric powered Cessna 337 Skymaster on what it calls an “actual airline route”, between two of Hawaii’s islands.

On 22 November, the company flew the modified aircraft, which it calls the Electric EEL, on a round trip from Kahului to Hana, both on Maui – a 20min flight of about 24nm (45km). The Electric EEL completed the round trip on a single battery charge, Ampaire says. Ampaire says the Kahului-Hana flight makes it the first company “to complete a demonstration flight of a hybrid-electric aircraft along an actual airline route”. Ampaire is performing demonstration flights in Hawaii via a partnership with local intra-island carrier Mokulele Airlines. Kevin Noertker, Ampaire chief executive, says the flights will demonstrate the “robustness of Ampaire’s technology” and aid development of future projects. Cessna 337s have two piston engines – one driving a forward-facing prop, the other driving a pusher prop. For the EEL, Ampaire replaced the six-seat aircraft’s forward engine with an electric system “capable” of producing 160kW, it says. The 300hp rear engine remains in place. Mokulele has signed a “letter of interest” to acquire aircraft from Ampaire, and the EEL project has support from Mokulele parent Southern Airways. ◗

[carlosebanegas-blog]

The Governance of Unmanned Aircraft Systems (UAS): Aviation Law, Human Rights, and the Free Movement of Data in the EU

The paper deals with the governance of Unmanned Aircraft Systems (UAS) in European law. Three different kinds of balance have been struck between multiple regulatory systems, in accordance with the sector of the governance of UAS which is taken into account. The first model regards the field of civil aviation law and its European Union (EU)’s regulation: the model looks like a traditional mix of top-down regulation  and  soft  law.  The  second  model  concerns  the  EU  general  data  protection  law,  the GDPR, which has set up a co-regulatory framework summed up with the principle of accountability also, but not only, in the field of drones. The third model of governance has been adopted by the EU through methods of legal experimentation and coordination mechanisms for UAS. The overall aim of the paper is to elucidate the ways in which such three models interact, insisting on differences and similari-ties  with  other  technologies  (e.g.  self-driving  cars),  and  further  legal  systems  (e.g.  the US) .

Over the past 15 years, scholars have increasingly focused on the normative chal-lenges  of  Unmanned  Aircraft  Vehicles  (UAV),  and  Systems  (UAS),  also  popu-larly  known  as  drones.  First,  the  attention  was  drawn  to  the  military  use  of  this  technology since the mid 2000s, that is, during the first years of the second Gulf War  in  Iraq  (and  in  Pakistan).  Whilst,  in  his  2010  Report  to  the  UN  General  Assembly, the Special Rapporteur on extrajudicial, summary or arbitrary execu-tions, Christof Heyns, urged the then Secretary-General Ban Ki-moon to convene a group of experts in order to address “the fundamental question of whether lethal force should ever be permitted to be fully automated,” another UN Special Rap-porteur, Philip Alston, declared that same year that “a missile fired from a drone is no different from any other commonly used weapon... The critical legal ques-tion  is  the  same  for  each  weapon:  whether  its  specific  use  complies  with  IHL,”  i.e. current international humanitarian law (in Pagallo 2013, at 4 and 59). A dec-ade later, this kind of debate is still wide open.The use of drones, however, can also affect the civil (as opposed to the state and the  military)  sector.  This  is  the  field  under  scrutiny  in  this  paper.  Scholars  have  examined matters of safety and security, drones market growth, public trust or dis-trust,  up  to  the  regulatory  efforts  of  national  and  international  lawmakers.  Their  latter  aim  is  to  reform  current  air  traffic  management  systems,  so  that  UAVs  and  UAS can gradually start sharing such air space with traditional aircrafts. In the US, for  example,  the  2012  FAA  Modernization  and  Reform  Act,  i.e.  Public  Law  112-95,  together  with  the  FAA  Reauthorization  Act  of  2018  provide  for  a  federal  legal  framework, which is complemented by the powers of the Federal Aviation Adminis-tration (FAA) and, to some of extent, the States of the Union. In the European Union (EU), a similar path has been followed by Regulation 2018/1139 on common rules in the field of civil aviation. By repealing the previous Regulation 2008/216, the new set  of  rules  reduces  powers  and  competences  of  both  Member  States  and  national  agencies  on  drones  operations,  by  devolving  most  of  the  relevant  ruling  powers  to  the European Commission and to the European Aviation Safety Agency (EASA).The aim of the paper is to restrict the focus of the analysis to the EU regula-tory  efforts  in  the  civil  sector,  in  order  to  cast  light  on  different  models  of  legal  governance  that  EU  lawmakers  have  adopted  in  the  fields  of  civil  aviation  law,  human rights protection, and data protection law with the free flow of such data. At the international law level, the notion of governance is usually related to “the formation and stewardship of the formal and informal rules that regulate the pub-lic realm, the arena in which state as well as economic and societal actors interact to make decisions” (Grindle 2007). Such formal and informal rules strike differ-ent  forms  of  balance  between  multiple  regulatory  systems,  such  as  the  forces  of  the market and of social norms, between law, ethics, and technology. One of the main contentions of this paper is that such balances vary in accordance with the specific sector of the governance of UAS which is taken into account in EU law.Next,  Sect. 2  sets  the  level  of  abstraction  of  this  paper,  by  distinguishing  three  forms  of  legal  regulation  with  their  variables.  Then,  Sect. 3  illustrates  the On Legal Regulation and its VariablesLegal regulation is an essential ingredient of most notions and models of governance (Pagallo 2015).  By  taking  into  account  the  regulatory  aims  of  the  law,  we  should  distinguish three kinds of legal regulation, i.e., between (i) traditional forms of top-down  regulation,  such  as  an  act,  or  a  statute,  which  mostly  hinge  on  the  threat  of  physical or pecuniary sanctions; (ii) manifold ways of self-regulation, or bottom-up approaches, with limited accountability and legal framing; and (iii) forms of co-reg-ulation that can be understood as a sort of interface between top-down and bottom-up solutions, between legislators and stakeholders.This basic demarcation between different forms of legal regulation and hence, of governance can be further developed with the variables of each observable of the  analysis.  As  to  the  forms  of  top-down  regulation,  lawyers,  especially  in  the  international  law  field,  distinguish  between  monistic  and  dualistic  approaches.  Monism refers to the functioning of a legal system—or to the interaction between two  or  more  legal  systems—which  is  ultimately  based  on  a  single  legal  source,  such  as  the  constitution  of  a  state.  Dualism  has  to  do  with  the  distribution  of  competences and coordination between two or more legal systems, each of which has  its  own  constitution,  or  basic  legal  source.  For  example,  it  is  still  an  open  issue  whether  the  EU  law  should  be  grasped  either  in  monistic  terms,  or  in  a  dualistic  manner:  the  EU  Court  of  Justice’s  doctrine  is  monistic,  whilst  both  the  German  and  Italian  constitutional  courts  endorse  a  dualistic  approach.  This  alternative affects the international regulations of UAS as well. Such regulations comprise  the  Chicago  Convention  from  1944  with  its  Annexes  (and  subsequent  amendments), much as the soft law provided by ICAO through its standards and recommended  practices  (Masutti  and  Tomasello  2018).  Although  the  latter  do  not have the same binding force of the Convention, the Contracting States should collaborate  in  securing  that  their  national  regulations  are  uniform  with  such  standards  and  recommended  practices.  This  form  of  international  cooperation,  however, according to certain scholars, should be strengthened through the devel-opment  of  a  proper  international  legal  framework  for  UAS,  due  to  the  unique  challenges  brought  forth  by  this  technology  and  the  need  to  develop  and  timely  adopt new standards (Fiallos 2016).Current  debates  on  the  international  laws  of  UAS,  regardless  of  the  monistic  or  dualistic  nature  of  this  law,  show  nonetheless  that  such  regulations  leave  room  for  different models of governance at the ‘regional level,’ e.g. the EU laws in the field of UAS. It is noteworthy that all the legal sectors under investigation in this paper, such as the fields of civil aviation law and of data protection, present a double level of top-down intervention, namely, that of the EU member states (national level), and that  of  the  EU  (international  or  quasi-federal  level).  Yet,  it  is  up  to  the  EU  and  its  Member States to determine how this double level of top-down intervention should actually  work.  After  all,  the  EU  lawmakers  have  adopted  two  different  regulatory  models  in  the  field  of  UAS  over  the  past  12  years,  i.e.  the  fragmented  and  dual  approach  of  Reg.  (EC)  2008/216  and  the  centralized  legal  framework  of  Regula-tion (EU) 2018/1139. One of the main aims of this paper will be to complement the analysis  of  such  models  of  top-down  regulation,  whether  national  or  international,  whether  monistic  or  dualistic,  with  further  forms  of  legal  governance  endorsed  by  the EU legislators in the field of UAS.As  regards  the  second  observable  of  the  analysis,  i.e.  the  notion  of  self-regula-tion, there are multiple bottom-up solutions. For instance, according to Chris Mars-den’s “Beaufort scale” (Marsden 2011), eight different levels of self-regulation can be  singled  out,  from  ‘pure’  unenforced  forms  of  self-regulation,  such  as  in  Second  Life (scale 0), to ‘approved’ self-regulation, as in Hotline (scale 8). These forms of limited accountability and legal framing are not particularly relevant in the context of  UAS  regulation  and  its  governance.  Rather,  such  bottom-up  solutions  should  be  scrutinized in connection with further forms of co-regulation, as a sort of legal link between legislators and stakeholders.Yet, also the notion of co-regulation has its own variables. This interface between top-down  and  bottom-up  approaches  includes  forms  of  approved  compulsory  self-regulation  (e.g.  ICANN),  and  scrutinized  self-regulation  (NICAM),  down  to  inde-pendent  bodies  with  stakeholder  fora,  in  which  top-down  directives  of  the  govern-ment are co-regulated through taxation and/or compulsory levy (Marsden 2011). In addition  to  these  forms  of  co-regulation,  we  should  take  into  account  the  account-ability  principle  of  the  EU  data  protection  regulation,  the  ‘GDPR’  (see  below  in  Sect. 5);  much  as  the  coordination  mechanisms  of  legal  experimentation  (Sect. 6). This  differentiation  between  multiple  forms  of  co-regulation  is  critical,  since  it  allows us to understand how the bar is set between the ends of the regulatory spec-trum, that is, between strict top-down and pure bottom-up regulations.In light of this threefold class of legal regulation, we can say that each regulatory solution  strikes  a  different  kind  of  balance  between  multiple  regulatory  systems  in  competition.  As  mentioned  above  in  the  introduction,  one  of  our  main  contentions  is  that  different  kinds  of  balance  have  been  struck  in  the  field  of  UAS,  in  accord-ance with the sector that is scrutinized under EU law. The next section examines the current state-of-the-art in civil aviation law, in order to pinpoint what model of legal governance the EU legislators have opted for in this field.3   On Civil Aviation in EU and its Model of Legal GovernanceUAS operations in Europe are currently disciplined by Regulation (EU) 2018/1139 on common rules in the field of civil aviation, the so-called “new basic regulation.” The  new  set  of  rules  repealed  the  dual  approach  of  the  previous  2008  regulation,  i.e. Reg. (EC) 2008/216. According to this latter legal framework, the EU lawmak-ers only provided rules for UAS with an operating mass over 150 kg and expressly excluded the regulation of certain types of drones, either due to their activity or their weight. This means that each EU Member State and their national aviation agencies had  regulatory  powers  for  all  the  other  kinds  of  drones  throughout  a  decade.  This  meant  however  the  fragmentation  of  the  system.  A  number  of  extremely  detailed  regulations by multiple national authorities raised the risk of hindering this vibrant field of technological innovation. The swirl of administrative acts by the Italian civil aviation authority, i.e. “ENAC,” illustrated this deadlock in the mid 2010s (Pagallo 2017a).In  order  to  guarantee  certainty,  harmonization  and  clarification  of  the  rules  on  drones, the new 2018 EU regulation sets up a centralized, top-down framework, in which  the  main  ruling  powers  are  devolved  to  both  the  European  Commission  and  the  European  Aviation  Safety  Agency  (EASA).  The  new  regulation  is  adopted  in  the  name  of  the  subsidiarity  principle.  The  latter  governs  the  exercise  of  the  EU’s  competences, as laid down in the Treaty of the European Union (Article 5(3)), and applies to all the cases in which the Union has no exclusive competence, as for civil aviation.  In  the  wording  of  the  new  Act,  “since  the  objectives  of  this  Regulation,  namely  establishing  and  maintaining  a  high  uniform  level  of  civil  aviation  safety,  while  ensuring  a  high  uniform  level  of  environmental  protection,  cannot  be  suffi-ciently achieved by the Member States because of the largely transnational nature of aviation and its complexity, but can rather, by reason of their Union-wide scope, be better  achieved  at  Union  level,  the  Union  may  adopt  measures,  in  accordance  with  the principle of subsidiarity” (Rec. 88).The new basic regulation concerns all drones regardless of their size and weight, although  there  are  some  exceptions,  which  are  up  to  EASA  to  regulate  with  its  guidelines,  pursuant  to  Annex  I  and  Art.  141(4)  of  the  regulation.  Member  States  can lay down specific national rules for UAS, either by granting specific exemptions to some European requirements, or amending the implementing and delegated acts of  the  Commission,  in  accordance  with  Art.  56(8)  and  71  of  the  regulation  (Bassi  2019a). However, the aim to guarantee standards for the safety, efficiency and envi-ronmental impact of air traffic—so that drones can gradually begin to share the air space—is  mostly  defined  at  the  EU  level.  Similarly  to  the  US  regulatory  model,  which  mostly  revolves  around  the  powers  of  the  Congress  and  the  Federal  Avia-tion Administration, the regulatory powers of the EU are devolved both to the Com-mission  and  to  EASA.  Since  2019  onwards,  scholars  had  thus  to  pay  attention  to  the  European  Commission’s  implementing  and  delegated  acts,  mandated  by  Reg.  2018/1139.  Such  acts  establish  a  specific  set  of  detailed  rules  for  different  classes  of  UAS  operations  (Bassi  2020).  Examples  are  the  Delegated  Regulation  (EU)  2019/945  on  unmanned  aircraft  systems  and  on  third-country  operators  of  UAS,  and  the  Implementing  Regulation  (EU)  2019/947  on  the  rules  and  procedures  for  the operation of unmanned aircrafts, as amended by the Commission Implementing Regulation (EU) 2020/639 of 12 May 2020, related to standard scenarios for opera-tions executed in or beyond the visual line of sight.In  addition,  there  are  the  regulatory  powers  of  EASA.  They  are  both  hard  and  soft.  As  to  the  hard  tools  of  EASA,  pursuant  to  Art.  75(2)(b)  of  Reg.  1139/2018,  the  Agency  has  the  power  to  develop,  upon  request  of  the  Commission,  technical  rules that cannot be changed by the Commission without prior coordination with the Agency.  This  power  of  EASA  is  disciplined  by  Article  115(1)  of  Regulation  (EU)  2018/1139  and  by  an  ad  hoc  internal  ‘Rulemaking  Procedure’  (EASA  2015)  (MB  Dec. No 18-2015). As regards the soft powers of EASA, the Agency can issue such acts, as the Guidance Material and Acceptable Means of Compliance that flesh out the  measures  to  comply  with  the  regulation,  including  e.g.  the  description  of  the  methodology for conducting a Specific Operation Risk Assessment and the model of a pre-defined risk assessment.Two  basic  features  of  this  regulatory  model  of  governance  for  UAS  in  the  civil  aviation  field  can  be  further  stressed  in  light  of  the  current  regulation  of  autono-mous ground vehicles (AVs), or self-driving cars. Although UAS and AVs may look somehow  similar,  the  ways  in  which  they  are  disciplined  in  the  EU  suggests  some  striking  differences.  In  addition  to  technological  and  geo-political  reasons  (Pagallo  2011), such different regulatory approaches concern alternative models of top-down regulation, and their interplay with the soft tools of the law. As to the different types of top-down regulation, in addition to Regulation (EU) 2018/113 in the field of civil aviation, there is a set of common rules established at the EU level also in the field of AVs. The list includes both a regulation on the approval and market surveillance of  motor  vehicles,  and  three  directives  on  liability  for  defective  products,  the  sale  of consumer goods, and insurance against civil liability (Pagallo et al. 2019). Con-trary  to  the  field  of  UAS,  however,  the  most  critical  legal  issues  of  current  traffic  law  depend  on  the  legislation  of  each  EU  member  state,  as  occurs  with  matters  of  redress,  damages,  or  tortuous  liability.  We  are  far  from  even  beginning  to  imagine  a quasi-federal legal framework for the use of AVs at the EU level. All the amend-ments which have been made to existing traffic laws, in order to allow for the testing and use of driverless technology on public roadways, are up to national legislators: Spain  passed  its  own  law  with  the  Dirección  General  de  Tráfico  from  November  2015; Belgium with the Royal Order from March 2016; Italy with the “Smart Road” decree from February 2018; France with the norms on “la croissance et la transfor-mation des entreprises” from April 2019; and so on. Although both regulatory mod-els of civil aviation and road traffic laws are thus top-down and dualistic—because there is a distribution of competences between the EU and its member states—only the regulatory framework of UAS appears highly centralized.A second crucial difference between UAS and AVs, and hence, another crucial facet of the EU regulatory model of governance for UAS has to do with the role of soft law. The lack of any robust soft law for AVs, as a matter of fact, appears as the by-product   of an on-going process to determine the rules of hard law in that field. As regards the governance  of  UAS,  the  soft  powers  of  EASA  can  hardly  be  overestimated.  They  are  established by Articles 75 and 76 of the basic regulation, and comprise (i) opinions and recommendations on the current legal framework; (ii) the development of standards for the integration of UAS operations in the single European sky strategy; (iii) monitoring functions that regard the application of the 2018 regulation; and, (iv) the coordination of the activities by member states, which includes certifications, duties of oversight—in  particular  cooperative  and  cross-border  oversight—and  enforcement  tasks  (Bassi  2020).Some of these soft powers of EASA on e.g. development of standards can be prop-erly  conceived  of  as  the  middle  ground  between  the  top-down  regulatory  approach  illustrated thus far, and the forces of the market. According to a study of the EU institu-tions, the drone services market is going to grow noticeably, with estimates “between €10bn by 2035 and €127bn for the coming years” (European Commission 2017). Yet, such growth would be impossible without efforts of coordination and cooperation with the drone industry. Going back to EASA’s Guidance Materials and Acceptable Means of Compliance, it is remarkable that the principal aim of such acts is to assist operators, for example, when applying for an authorization in the specific category of the opera-tion to be performed. In the description of the rulemaking procedure followed for the adoption of its Opinion 5/2019, EASA has stressed that the definition of standard sce-narios for specific drones operations is developed on the basis of the “in-service experi-ence of some Member States.” Stakeholders and national experts of different member states are involved in the process (EASA 2019).The EU top-down regulatory approach to the field of civil aviation is thus crucially complemented, all in all, by the soft tools of the law. Soft law represents the interface between  the  common  standards  on  safety,  efficiency  and  environmental  impact  of  the  air traffic—as the main goals of the current reform of the air traffic management system in Europe—and the role that the forces of the market play in this context. The overall aim of the EU lawmakers is to attain that the whole framework, including UAS shar-ing the air space with traditional aircrafts, is at full speed by 12 September 2023, i.e. as established in Article 140 of the 2018 Regulation.Still, the governance of UAS and the legal regulations of the sector regard also but not only the field of civil aviation. UAS affect further fields as different as public secu-rity  legislation,  telecommunication  and  data  protection  law,  product  liability,  criminal  law, or insurance law (Custers 2016). Attention should be drawn as well to the impact of UAS operations on the protection of people’s rights, such as the right to dignity and freedom  of  assembly  and  association,  privacy  and  non-discrimination,  down  to  the  criminal safeguards of the individuals (Finn and Wright 2012). The next section exam-ines what model of governance may follow as a result of this broader view on the nor-mative impact of UAS.

4   When Drones Meet People’s RightsScholars and authorities—such as the Art. 29 Working Party, mentioned above in the  introduction—have  time  and  again  stressed  threats  and  challenges  triggered  by  the  use  of  drones.  Such  threats  include  a  “chilling  effect;  dehumanisation  of  the surveilled; transparency and visibility, accountability and voyeurism; function creep; bodily privacy; privacy of location and space; and privacy of association” (Finn and Donovan 2016).The  provisions  and  legal  safeguards  that  are  hence  at  stake  with  the  use  of  drones  regard  acts  and  statutes  of  national  states  with  their  constitutions,  much  as  international  conventions  and  agreements.  In  Europe,  for  example,  attention  should be drawn to a long-standing tradition, which is defined by the 1950 Con-vention  on  Human  Rights  (“ECHR”),  and  the  2000  EU  Charter  of  Fundamental  Rights  (“CFR”).  In  the  case  of  the  ECHR,  the  legal  reference  is  to  the  human  nature of such rights, in accordance with the terminology of international lawyers and  due  to  the  international  nature  of  the  convention.  In  the  case  of  the  CFR,  the  reference  is  to  the  fundamental  character  of  the  rights,  because  of  the  con-stitutional relevance of the Charter in the system of legal sources in the EU. On this  basis,  scholars  have  examined  whether  this  set  of  rights,  both  “human”  and  “fundamental,” can properly tackle the normative challenges brought about by the use of drones in the civil sector, or whether further advancements in the technol-ogy, e.g. the use of highly sophisticated AI drones, may fall within the loopholes of the legal system, as occurs, for example, in the field of the laws of war and of international humanitarian law (Pagallo 2013).Such  alternative  on  either  opting  for  the  enforcement  or  the  amendment  of  today’s drone regulations in the civil sector does not seem to affect, however, the model of legal governance illustrated so far. On the one hand, the enforcement of today’s laws by national and international courts, such as the European Court of Human Rights in Strasbourg, or the EU Court of Justice in Luxembourg, comple-ments the top-down rules set up by governments and legislators through the case law of such courts. This is the approach of the Art. 29 Working Party in the 2015 Opinion  on  the  use  of  drones  (wp231),  as  mentioned  above  in  the  introduction.  In  that  Opinion,  the  EU  data  protection  authorities  insisted  on  how  UAS  opera-tions should abide by the “universal values of human dignity” (Protocol 13 to the ECHR and Art. 1 of the CFR); “freedom” (Section I of both the ECHR and the CFR); “equality” (ECHR’s Protocol 12 and CFR’s Art. 20); and so forth.On the other hand, we may admit that current advancements in technology will require a new generation of rights and principles, in addition to the list enshrined in  national  constitutions  and  international  agreements.  For  example,  by  taking  into account the normative challenges that are unique to AI, scholars have stressed the limits of traditional principles, such as justice and autonomy, beneficence and non-maleficence, and hence, the need of enabling such principles through a new one:  the  principle  of  “explicability”  (Floridi  et  al.  2018).  Even  in  this  case,  we  should concede however that the top-down regulatory model discussed in the pre-vious section would not be challenged. Whilst current discussions on the ethical and  legal  principles  of  AI  and  of  other  emerging  technologies  revolve  around  whether and to what extent policy makers and legislators have to endorse a new set of principles and rights, the ultimate end is to make both new and old rights enforceable.  Therefore,  should  our  conclusion  be  that  the  protection  of  people’s  rights, vis-à-vis the use of drones in the civil sector, does not entail any new form of legal governance?We  think  there  is  a  relevant  ‘exception.’  It  regards  the  field  of  data  governance  and  the  corresponding  right  to  personal  data  protection  in  EU  law.  Article  132  of  the civil aviation regulation includes a safeguard clause for privacy concerns, which refers  to  the  application  of  the  General  Data  Protection  Regulation  (GDPR)  Reg.  (EU)  2016/679  and  of  the  Regulation  (EC)  no.  45/2001  (repealed  by  Reg.  (EU)  2018/1725).  This  does  not  mean  that  every  UAS  operation  necessarily  entails  the  processing  of  personal  data,  yet,  manifold  UAS  applications  for  public  or  private  surveillance, disaster relief or medical assistance, journalism or simple leisure, up to a fascinating variety of commercial services do involve the collection and process-ing  of  personal  data  (Art.  29  WP  2015).  Accordingly,  scholars  have  examined  the  several ways in which drone operators and manufacturers should comply with both constraints  and  principles  of  the  GDPR,  such  as  the  purpose  limitation  principle,  data  minimisation,  individual  consent,  storage  limitation,  and  so  forth.  The  atten-tion  has  been  also  drawn  to  the  data  protection  impact  assessments  set  up  by  Art.  35 of the GDPR, and how the latter may relate to the operational risk assessment of Art. 11 Reg. (EU) 2019/947 on rules and procedures for the operation of unmanned aircraft (Bassi 2020). On top of that, a growing amount of work has been devoted to the implementation of Art. 25 of the GDPR, namely, how to set up a new generation of  GDPR-abiding  drones  in  accordance  with  both  the  principles  of  data  protection  by design, and by default (Bassi et al. 2019).Notwithstanding this amount of work on UAS and data protection, there are still few  studies  on  the  model  of  legal  governance  set  up  by  the  GDPR  (Pagallo  et  al.  2019); and moreover, on how this model may relate to that which was under scrutiny above  in  the  previous  section,  i.e.  the  model  of  legal  governance  for  UAS  in  civil  aviation law. The next section aims to fill this gap in today’s research.5   On Personal Data Protection and its Governance in EU LawThe  GDPR  is  a  long  and  complex  legal  text,  which  includes  173  recitals  and  99  articles, some of which appear rather vague or opaque. According to certain schol-ars,  “the  GDPR  can  be  a  toothless  or  a  powerful  mechanism  to  protect  data  sub-jects dependent upon its eventual legal interpretation: the wording of the regulation allows either to be true” (Mittelstadt et al. 2016; Pagallo 2017b).The  overall  architecture  of  this  regulation  looks  however  clear.  The  model  adopted by the EU legislators, pursuant to the definitions illustrated above in Sect. 2, is a co-regulatory model of legal governance. The legal link between the top-down norms of the regulation and the self-regulatory choices of data controllers is given by the accountability principle enshrined in Art. 5 of the GDPR. On the one hand, Art. 5(1) lists six sets of principles that should be implemented by data controllers These  principles  regard  (i)  lawfulness,  fairness,  and  transparency  of  data  process-ing; (ii) purpose limitation; (iii) data minimization; (iv) accuracy; (v) storage limita-tion; and, (vi) integrity and confidentiality. On the other hand, Art. 5(2) leaves room for  self-regulatory  measures,  both  technical  and  organizational,  on  the  part  of  the  data controllers, as to how they should attain the outcomes established by Art. 5(1), under  the  supervision  of  public  guardians.  Although  not  mentioned,  the  principle  of accountability is similarly at work with the provision of Article 24(1): “the con-troller shall implement appropriate technical and organisational measures to ensure and to be able to demonstrate that processing is performed in accordance with this Regulation.”The overall idea of the GDPR’s co-regulatory model is that personal data process-ing is a risky activity and nobody, better than data controllers know how to properly tackle the risks of their own data processing. This is why the logic of the account-ability  principle  also  operates  with  the  provisions  of  Art.  25(1)  on  the  principle  of  data protection by design and by default, of Art. 32 on the “security of processing,” and of Art. 35 on data protection impact assessments. Safeguards should indeed be pre-emptive, rather than simply remedial, and do not regard just those data subjects concerned by the processing, much as design solutions and organizational measures should abide by all the requisites of the regulation (Pagallo et al. 2019).We may thus wonder how the co-regulatory model of data governance set up by the GDPR relates to the top-down regulatory approach of the EU civil aviation regu-lation  in  the  field  of  UAS.  A  sound  hypothesis  suggests  that  we  should  grasp  both  regulations  EU—2016/679  (i.e.  data  protection)  and  2018/1139  (i.e.  civil  aviation)  as  complementary.  This  means  that  UAS  operators,  on  the  one  hand,  shall  always  abide  by  the  top-down  rules  on  e.g.  safety  and  security  established  by  the  EU  leg-islators  in  the  field  of  civil  aviation—eventually  with  the  assistance  and  guide  of  EASA,  as  regards  certifications  and  means  of  compliance—whereas,  on  the  other  hand,  if  such  UAS  operations  entail  the  processing  of  personal  data,  it  is  up  to  the  data  controller  to  organize  itself,  in  order  to  comply  with  the  six  sets  of  principles  enshrined in Art. 5(1) of the GDPR.The greater flexibility of the co-regulatory approach of the GDPR—vis-à-vis the top-down regulations of EU-2018/1139—may depend on two main facts. First, the speed  of  innovation  that  mostly  distinguishes  the  field  of  data-driven  technologies  has  suggested  more  adaptability  than  the  top-down  and  soft  law  approach  to  civil  aviation. Second, the long and well-established tradition of safety design assurance in the field of civil aviation has supported the most rigid approach of the correspond-ing regulation. However, in both fields of data protection and civil aviation, legisla-tors have to address the common problem to design a set of rules, which should nei-ther  hinder  the  advance  of  technology,  nor  require  over-frequent  revision  to  tackle  such  a  progress  (Pagallo  2017c).  We  return  to  this  problem  of  techno-regulation  below in the next section.The complementarity hypothesis on how to grasp the interaction between regula-tions  EU—2016/679  (i.e.  data  protection)  and  2018/1139  (i.e.  civil  aviation),  has  still some problems. The first open issue brings us back to the data protection impact assessments set up by Art. 35 of the GDPR and the operational risk assessment of Art. 11 Reg. 2019/947. Here, we face a chicken and egg dilemma. According to the GDPR,  an  impact  assessment  (“DPIA”)  is  mandatory  when  personal  data  process-ing  entails  high  risks  for  the  rights  and  freedoms  of  natural  persons,  “in  particular  using new technologies” (Art. 35(1)). Likewise, Art. 18(h) and (i) of Reg. 2019/947 impose on each member state a twofold duty, namely, to develop a “risk-based over-sight  system”  for  certain  UAS  operators  and  an  “audit  planning  based  on  the  risk  profile, compliance level and the safety performance of UAS operators.” As a result, should the latter audit presuppose a UAS DPIA pursuant to Article 35 of the GDPR, or the other way around?The second problem of the complementarity hypothesis regards the limits of the GDPR. As stressed above in Sect. 3, UAS operations do not only concern the pro-cessing of personal data, but also public security legislation and criminal law, rules on product liability and insurance law, telecommunication regulations, down to the processing of non personal data. Some of these issues shall be regulated under the “U-space services” developed by EASA, as the latter stressed in its draft for a Com-mission  Implementing  Regulation  on  a  high-level  regulatory  framework  (EASA  2020b), proposed in Opinion 01/2020 (EASA 2020a). Still, how the norms on civil aviation should relate to the complexity of such other fields of the current legal regu-latory framework remains often unclear (Bassi 2020). Some of these fields, e.g. tor-tious liability, mostly fall within the regulatory powers of EU member states, so that risks of fragmentation are high.A third trouble with the complementarity hypothesis concerns how the top-down approach of the civil aviation regulation can cope with the advancement of technol-ogy vis-à-vis the more flexible co-regulatory approach of the GDPR. Section 3 has already mentioned the role of EASA’s soft law in developing rules and standards for the integration of UAS operations within the Single European Sky strategy, and yet, this approach does not seem sufficiently adaptable. Even EU legislators and policy makers increasingly admit this (Pagallo et al. 2019).Is there any further model of governance that can help us tackle the intricacies of technological innovation?6   Legal Experimentations and Data GovernanceThe  aim  of  technological  regulation  should  be  to  strike  a  fair  balance  between  the  protection  of  people’s  rights  and  interests,  on  the  one  hand,  and  the  development  of  sound  technological  research  and  innovation,  on  the  other.  Over  the  past  years,  scholars—and even more importantly, legislators and policy makers—have increas-ingly  noticed  that  the  more  technology  is  complex,  the  less  traditional  top-down  approaches  are  fruitful,  in  order  to  properly  address  the  normative  challenges  of  technology. Scholars and policy makers have accordingly examined alternative ways to govern the manifold fields of technological innovation.The previous section has examined one of such alternative ways, i.e. the co-regu-latory model of data governance set up by the GDPR with the principle of account-ability.  A  problem  with  this  approach,  however,  regards  its  limits.  We  often  lack  a  set  of  common  principles  to  be  enforced  in  many  vibrant  fields  of  technologi-cal  research,  as  occurs  with  the  six  sets  of  principles  enshrined  in  Art.  5(1)  of  the GDPR. The on-going debate on the ethical principles of Artificial Intelligence (AI) and the consequent amendments to the current legal framework suggest that we can hardly transplant the co-regulatory model of the GDPR into other domains of tech-nological regulation. Scholars and policy makers have thus considered further forms of regulation between top-down and bottom-up solutions. Section 2 mentioned some of them, such as forms of approved compulsory self-regulation, scrutinized self-reg-ulation,  or  the  setting  of  independent  bodies  with  stakeholder  fora.  Still,  these  co-regulatory forms of legal governance fall often short in coping with crucial features of today’s technology, such as the lack of data about the probability of events, con-sequences, and costs, which should allow us to determine the level of risk (Pagallo 2017a). EASA has denounced this lack of data in its Opinion 01/2020.The  Agency  proposed  a  “High-level  regulatory  framework  for  the  U-space,”  which includes the impact assessment presented by EASA for the draft of the pro-posed  regulation.  As  the  Agency  admits,  “as  there  is  no  sufficient  data  to  perform  a  through  quantitative  safety  risk  assessment  of  the  proposed  regulation,  EASA  will use a general qualitative approach to conduct the safety risk assessment of the options  analysed  in  this  impact  assessment.”  According  to  the  Agency,  we  should  add  to  this  lack  of  data  the  lack  of  a  “common  data  exchange  infrastructure.”  In  the Opinion of EASA, the idea is that such constraints should be addressed through monitoring  procedures.  The  regulatory  model  of  governance  we  are  looking  for  should  indeed  provide  the  legal  basis  for  collecting  the  empirical  data  and  knowl-edge  necessary  for  making  rational  decisions  on  a  number  of  critical  issues,  for  example,  in  order  to  better  appreciate  the  threats  associated  with  a  certain  techno-logical  application,  such  as  a  urban  drone  flight,  a  bunch  of  self-driving  cars,  or  a  team  of  service  robots.  This  kind  of  factual  information  is  a  necessary  condition  for  every  sound  model  of  legal  governance  today  (Pagallo  2017a).  In  the  wording  of  EASA,  it’s  crucial  “a  continuous  and  systematic  process  of  data  collection  and  analysis about the implementation/application of a rule/activity. It generates factual information for future possible evaluations and impact assessments. It also helps to identify actual implementation problems and support regular updates of the regula-tory framework” (EASA 2020a).Another  crucial  ingredient  of  the  model  has  to  do  with  the  role  of  stakeholders  and how they should be involved: we already stressed this point above in Sect. 3, in connection with EASA’s soft law tools and the development of standards in the field of UAS. The increasing use of drones for journalism and surveillance, medical assis-tance and commercial services, or just for fun and leisure, suggests that we should take into account the role of social standards, in addition to the development of tech-nological  standards.  As  shown  by  the  use  of  drones  during  the  Covid-19  crisis  in  urban  areas,  UAS  clearly  affect  how  people  perceive  and  live  in  public  and  even  private spaces. Consultations with stakeholders and forms of participation related to the use of drones can increase both the awareness of social benefits and knowledge of best practices and recommended behaviours for diminishing risks for safety and privacy.  A  sound  model  of  governance  for  this  field  should  thus  include  forms  of  involvement for the alignment of societal values and comprehension of public opin-ion, much as responsible experimentation could improve our understanding of how highly sophisticated technological systems may satisfy human needs (Bassi 2019b) Remarkably,  this  latter  approach  to  experimentation  has  been  progressively  adopted  by  policy  makers  and  governments  over  the  past  two  decades  (Pagallo  2017a).  The  Japanese  government,  for  instance,  has  created  a  number  of  special  zones  for  the  empirical  testing  and  development  of  robotics  and  AI  systems.  Such  forms  of  living  labs,  or  Tokku,  have  concerned  so  far  the  fields  of  road  traffic  laws  (at Fukuoka in 2003), radio law (Kansai 2005), data protection (Kyoto 2008), safety governance  and  tax  regulation  (Tsukuba  2011),  much  as  road  traffic  laws  in  high-ways  (Sagami  2013).  These  forms  of  legal  experimentation  have  been  developed  in  Europe,  much  as  in  US  as  well.  Experiments  have  been  particularly  popular  in  the  field  of  self-driving  cars,  although  it  is  unsurprising  that  this  trend  has  rapidly  extended  to  the  drone  sector  as  well.  In  January  2019,  the  first  special  zone  for  drones  in  open  labs  was  established  in  the  harbour  of  Antwerp,  so  as  to  test  the  development of interoperability standards for communication systems. Further open labs have been created in other European cities, such as Turin, where an Open Lab is devoted—also but not only—to clarify the content of the rules and standards that privacy-friendly civilian UAS operations should abide by (Bassi 2020).Legal experiments can be perfomed through forms of experimentation by deroga-tion,  by  devolution,  or  by  “open  access,”  that  is,  “allowing  alternative  lawful  (col-laborative)  self-regulatory  practices  to  arise”  (Du  and  Heldeberg  2019).  What  all  these kinds of legal experiments have in common regards their mechanisms of coor-dination  (Pagallo  et  al.  2019).  As  a  model  of  smart  governance,  such  coordination  mechanisms represent the interface between the top-down regulatory efforts of leg-islators  and  the  bottom-up  solutions  of  self-regulation.  In  particular,  going  back  to  the co-regulatory models introduced above in Sect. 2, the coordination mechanisms of legal experimentation set the regulatory bar between the accountability principle of the GDPR and every model of self-regulation, either as a form of approved com-pulsory or scrutinized bottom-up approach. The bar is lower than the accountability principle’s,  because  the  coordination  mechanisms  of  legal  experimentation  lack  a  set of common values, such as the six sets of principles enshrined in Art. 5(1) of the GDPR. The regulatory bar is higher than in every model of self-regulation, because the perimeters of legal experimentation are defined by the legislator in a top-down way, that is, through e.g. public authorizations for security reasons, formal consent for  the  processing  and  use  of  personal  data,  mechanisms  of  distributing  risks  via  insurance models and authentication systems, and more (Pagallo 2017c).We  can  thus  wonder  how  this  governance  model  of  coordination  in  the  field  of  UAS may relate to the previous models illustrated so far, i.e. the top-down approach of  civil  aviation  law  supplemented  by  the  protection  of  people’s  rights  (as  seen  above  in  Sects. 3  and  4),  together  with  the  co-regulatory  approach  of  the  GDPR  (illustrated in Sect. 5).A well-established tradition in computer science suggests a solution through the middle-out approach (Pagallo et al. 2019). Both computer sciences and practical sci-ences  such  as  the  law  have  to  address  the  constraints  that  arise  during  the  design  process when upgrading existing systems. This is the case of the middle-out design for  human–computer  interaction  in  urban  spaces  (Fredericks  et  al.  2016),  or  when  building reference ontologies for the legal domain (El Ghosh et al. 2016). The same holds  true  in  the  field  of  UAS.  The  upgrading  of  the  system  through  experiments and  methods  of  coordination  shall  go  hand-in-hand  with  the  normative  constraints  set  up  by  both  the  regulations  on  civil  aviation  and  data  protection.  Such  experi-ments are in fact conducted in legally de-regulated special zones through the set of coordination  mechanisms  that  define  the  interface  of  the  governance  model.  Inter-estingly, this approach to what is also dubbed as “experimentalist governance” (Zeit-lin 2015), is at work with further initiatives in the field of data governance. Consider the European Commission’s policy on better and smart regulation (European Com-mission 2015),  and  the  EU  Better  Regulation  scheme  for  interoperability  (TOGAF  2017),  in  which  the  use  of  participation  schemes  and  coordination  mechanisms  can  be  understood  as  the  interface  of  the  model  between  top-down  and  bottom-up  solutions. In addition, the approach is consistent with the stance on the rule of law taken by standardisation agencies and some governance models in the business field (Pagallo et al. 2019; Poblet et al. 2019).This  convergence  is  unsurprising.  The  field  of  UAS  and  its  governance  have  shown  that  the  more  technological  regulation  is  complex,  the  less  top-down  and  bottom-up  approaches  are  fruitful,  and  the  more  we  should  pay  attention  to  forms  of co-regulation through the middle-out level of the analysis. The time is ripe for the conclusions of our study.7   

Conclusions

The paper has examined three models of governance for UAS in EU law for the civil sector, namely:(i) The top-down model of civil aviation law, supplemented by both the tools of soft law and the legal safeguards for the protection of human and fundamen-tal rights. This model highlighted both convergences between legal systems (e.g. the EU and US general laws on civil aviation), and differences between technologies (e.g. the decentralized regulation of self-driving cars in the EU vis-à-vis the centralized EU governance of UAS);   (ii) The co-regulatory model of data protection with the accountability principle enshrined in Art. 5 of the GDPR, which applies to all processing of personal data in the EU, regardless of the technology under scrutiny; and,  (iii)    The middle-out model of coordination mechanisms for legal experimentation, which has been increasingly adopted by most legal systems to tackle the chal-lenges of technological innovation.The  three  models  can  be  grasped  according  to  a  sort  of  legal  spectrum.  At  one  end of the spectrum, there are the strict top-down regulatory approaches that aim to govern both social and individual behaviour through the threat of physical or pecu-niary  sanctions,  whereas,  at  the  other  end  of  the  spectrum,  we  find  pure  self-regu-latory  solutions  with  limited  accountability  and  legal  framing.  In  light  of  the  three  models of UAS governance in civil aviation, data protection, and legal experimenta-tion, we can thus say that the bar of legal regulation is progressively lowered as we move from the first to the second model, i.e. from civil aviation to data protection;

and  from  the  second  to  the  third,  i.e.  from  data  protection  to  legal  experimenta-tion.  The  reason  why  the  regulatory  bar  is  progressively  lowered  depends  on  the  flexibility  that  is  necessary  to  properly  deal  with  the  normative  challenges  of  UAS  technologies.By lowering the regulatory bar, from strict top-down solutions (e.g. aircraft secu-rity), towards more flexible co-regulatory approaches (e.g. personal data processing by  UAS),  it  does  not  follow  that  the  bar  of  legal  safeguards  is  lowered  as  well.  In  the case of the GDPR’s model of data governance, the sets of principles of Art. 5(1) flesh  out  the  outcomes  that  data  controllers  should  attain  under  the  supervision  of  public guardians. As regards the coordination mechanisms of legal experimentation, lawmakers  determine  the  boundaries  of  the  legally  de-regulated  special  zones.  As  previously  stressed  in  Sects. 5  and  6,  the  governance  models  for  UAS  operations  should be grasped as complementary and in accordance with the goal which is taken into account, e.g. safety, efficiency, or environmental-friendly impact of UAS oper-ations  (first  model);  fair  processing  of  personal  data  (second  model);  or  empirical  testing for new standards (third model).The complementarity hypothesis leaves some issues open. Three of them are par-ticularly relevant for the governance of UAS. First, each model of governance is still in  progress.  The  civil  aviation  legal  framework  should  be  completed  within  2023;  data protection rules are often open to different interpretations; whereas legal exper-imentalism is instrumental to find out solutions for the previous models. Second, we mentioned  that  it  is  still  unclear  how  such  regulatory  models  should  complement  each  other  under  certain  circumstances,  e.g.  the  impact  assessments  set  up  by  Art.  35 of the GDPR vis-à-vis Art. 11 of Reg. 2019/947 on civil aviation. Third, further regulatory  issues  are  not  covered  by  such  models.  These  gaps  concern  either  the  EU law and its interaction with the legal systems of the member states, or between these latter legal systems with problems of coordination. Gaps include also but not only public security legislation and criminal law, rules on tortious liability and some aspects of insurance law. Problems of fragmentation follow as a result of the distri-bution, or coordination of regulatory powers, up to 27 different member states.This threefold set of open issues reminds us of the troubles of the law when deal-ing with the complexity of technology. The intricacy is corroborated by the threefold approach  endorsed  so  far  by  the  EU  institutions  for  the  governance  of  UAS.  The  complementarity and flexibility of the interaction between models may represent the only way in which the law can strike a fair balance between the protection of peo-ple’s rights and the development of sound technological research. In light of such a balance  between  safety  and  security,  data  protection  and  standards,  environmental-friendly  impact  of  UAS  operations  and  the  protection  of  human  and  fundamental  rights,  we  should  conclude  that  the  governance  of  UAS  is  such  a  complex  field  of  legal regulation that needs no single model, but three.

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Tracks to download

15-Dic-2013 Paul Oakenfold & Disfunktion feat. Spitfire - Beautiful World (Yonathan Zvi remix) Futuristic Polar Bears & Danny Howard - Thundergod Thomas Gold feat. Kaelyn Behr - Remember (Luke Carpenter Remix) Tom Staar feat. In Atlanta - Staars (In Atlanta Remix) Shuffle Inc. - All I Do (Main Vocal Mix) 9. Velvetine – The Great Divide 18. Sunlounger & Zara Taylor – Try To Be Love (Roger Shah Naughty Love Mix) 23. Armin van Buuren feat. Ana Criado – I’ll Listen 24. Aly & Fila meet Roger Shah feat. Adriana Thorpe – Perfect Love 25. Ana Criado & Omnia – No One Home 27. Ben Gold feat. The Glass Child – Fall With Me 28. Aruna – Save The Day (Myon & Shane 54 Summer Of Love Mix) 29. Ferry Corsten feat. Betsie Larkin – Not Coming Down (Dash Berlin 4AM Remix) 31. W&W – Shotgun 32. Heatbeat – Chow Mein 40. Andy Moor – K Ta 41. Andrew Bayer feat. Molly Bancroft – Keep Your Secrets (Myon & Shane 54 Summer Of Love Mix) Pascal FEOS - Inhale - Exhale Bachelors Of Science - Sirens Bachelors Of Science - People Together Nontone & Atsa Tsa - Lybov Erunda Rhye - Open (Keeno Remix) Majesa feat Adrina thorpe - who will find me in the end (armin van buuren mashup) Peter Martjin wijnia pres. Vs. Dj Shah Eelke Klein - ein tag am strand Cahb - secrets VIP John O’ Callaghan - earth2self Giuseppe Otoviani & audio cells feat Shannon Hurley - I am your shadow Ferry corsten - black light (original mix) Tiger paw - for you Feelin so high - Ji Ben Gong Wilkinson - redemption Luciana - I’m Still Hot (Revolver & Scotty Boy Remix) Fast Foot ft. LJ MTX - Drugs Sex Money Electro (Revolvr Remix) Scooter & Lavelle - Beats Inside My Head (Revolvr & Donald Glaude Rmx) Green Velvet - Answering Maching (Santiago & Bushido Remix) Mot1v - Ashore Luke Bond - Reflections Kaimo K - Firefly PM AttitudE - White Night (Passenger 75 Uplifting Remix) Franz - Emerge (Dreamy Remix) Abstract Vision & Elite Electronic - Always Loved U (Dallaz Project Remix) BT feat. Aqualung - Surrounded (Super8 & Tab Remix) Faruk Sabanci & Mark Sixma - Tripod Lana Del Rey - Young & Beautiful (Myon & Shane 54 Summer of Love Mix) Myon & Shane 54 feat. Natalie Peris - Outshine (Nigel Good Remix) Mike Balance - Dig This Chrizz Luvly - speculate Lonely - rezonate

Short Bus Kids - Writt'n a Song Wankelmut & Emma Louise - My Head Is A Jungle Aimoon – Cloud Breaker Mutated forms - crawling Kove - searching Milan & Phoenix - Istanbul (not Constantinople) Woody van Eysenck & Ruben de ronde - devan Judge Jules & corderoy - give me a reason (incl. reaves & ahorn remix) George Acosta feat. Tiff Lacey - I know ( beat service proglifting remix) Stefan biniak - mad in love Men at work - down under ( chuck Norris dub) Fatboy slim Calvin Harris rica star chuckie dzeko & Torres - eat sleep rave repeat down to this Michael knead - rainbow coloured picture Departure Ibiza 013 - dan barred Motorcycle - as the rush comes (high rankin remix) Arming can buuren feat. Cindy alma - don’t want to fight love away aurosonic feat. Kate Louis smith - open your eyes (progressive mix) Rudimental - waiting all night AUDIOJACK - this house MikeZ - his spirit Al Bradley - skirmish original mix Hard rock sofa swanky tunes - stop in mind Alex Hyde - get away (dimitri Vegas & like mike remix) CHILLHOP— Dirty Elegance - Wirrok Nujabes - Aruarian Dance Kondor - Promise Bonobo - Ten Tigers Karamel Kel - Mindstate Brock Berrigan - The Celebration Song Brock Berrigan - The plot Thickens Kontor 2013

Avicii - You Make Me Alesso vs OneRepublic - If I Lose Myself Armin van Buuren feat. Trevor Guthrie - This Is What It Feels Like (W&W Remix) Capital Cities - Safe And Sound (Tommie Sunshine & Live City Remix) Empire Of The Sun - Alive (David Guetta Remix) Theophilus London - Wine & Chocolates (andhim Remix) Tom Novy feat. Amadeas - Dancing In The Sun Sono - Keep Control (H.O.S.H. Mix) Alex C. feat. Lisa Rowe - Feed Me Diamonds Jack Holiday & Mike Candys - The Riddle Anthem 05. Bingo Players feat. Far East Movement - Get Up (Rattle) [para juan] Dimitri Vegas & Like Mike vs Sander van Doorn - Project T (Martin Garrix Remix) Tiësto - Adagio For Strings (Blasterjaxx Remix) 13. Blasterjaxx - Fifteen (Hardwell Edit) 18. Kat Krazy feat. Elkka - Siren

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Stoicism is based on the idea that anything which causes us to suffer in life is actually an error in our judgment, and that we should always have absolute control over our emotions. Rage, elation, depression are all simple flaws in a person’s reason, and thus, we are only emotionally weak when we allow ourselves to be. Put another way, the world is what we make of it.

Epicureanism argues that displeasures do exist in life and must be avoided, in order to enter a state of perfect mental peace (ataraxia, in Greek). Stoicism argues that mental peace must be acquired out of your own will not to let anything upset you. Death is a necessity, so why feel depressed when someone dies? Depression doesn’t help. It only hurts. Why get enraged over something? The rage will not result in anything good. And so, in controlling one’s emotions, a state of mental peace is brought about. Of importance is to shun desire: you may strive for what you need, but only that and nothing more. What you want will lead to excess, and excess doesn’t help, but hurts.

- Zeno of Citium, Philosopher founder of the school of Stoicism.

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=== Trance Top 100 2012.5 === (Presented by mp3s.su)

Tracklist: 001. Eluna - Severence (Markus Schulz vs. Elevation Remix) 002. Turn & Natali Kryzhanovski - Broken Dreams (Original Mix) 003. Oakenfold feat. Tamra Keenan - Maybe It’s Over (Organ Donors Perfecto Mix) 004. Ansar Alee - Retain 005. Ben Preston - Parallelism (Original Mix) 006. Binary Finary feat. Jordan Suckley - It Gets Me (Original Mix) 007. Bobina - Diamond Hell (Original Mix) 008. Chapter XJ - Believe (Original Mix) 009. Delacroix pres. Marell - Heart Of Mine (Yves De Lacroix & Marell’s Original Mix) 010. DJ Feel - It Comes (Original Mix) 011. Joint Operations Centre - Glyph (Original Mix) 012. JOOP - Focus (Original) 013. Mark Eteson & MerEdith Call - Together (Original Mix) 014. Miroslav Vrlik - See The Sun (Original Mix) 015. Omnia & IRA - The Fusion (Original Mix) 016. Protoculture - Cobalt (Original Mix) 017. Rave Channel - Illusion (Original Mix) 018. Reminder - On The Beach (Stoneface & Terminal Remix) 019. Saint X - Orion (Original Mix) 020. Santerna feat. Vadim Kapustin - I Believe In Life (Solis & Sean Truby Remix) 021. Sergey Nevone & Simon O'Shine - Balearic Island (Original Mix) 022. Shogun - Amplify 023. Space RockerZ feat. Ellie Lawson - So Out Of Reach (Original) 024. Starkillers & Nadia Ali - Keep It Coming (Basto Remix) 025. Super8 - Alba (Maor Levi Remix) 026. T-Amo - Restation (Original Mix) 027. The Thrillseekers feat. Fisher - Angel (Club Mix) 028. Timewave - Super Sonic (Original Mix) 029. Tomas Heredia - Hurricane (Original Mix) 030. Tritonal - Turbine (Original Mix) 031. Wezz Devall - Kill Of The Year (Original Mix) 032. Will Holland feat. Jeza - Every Heartbeat (Beat Service Intro Mix) 033. ATB feat. Ramona Nerra - Never Give Up (ClubMix) 034. Sean Truby & Craig Purvis - Beyond The Horizon 035. BT - Flaming June (Paul Van Dyk Remix) 036. Tangle & Mateusz - Solstice 037. Allure - I Am (Bart Claessen Remix) 038. Armin van Buuren - Orbion (Extended Version) 039. Evgeny Bardyuzha - Magnitoplan (Club Mix) 040. Imperfect Hope - Unforgettable (Traces Traxx Remix) 041. Misja Helsloot - Beyond Tomorrow (Marco Tangelder Remix) 042. Moonbeam feat. Avis Vox - Disappearance (Aerofeel5 Remix) 043. Orjan Nilsen - Endymion (Original Mix) 044. Ralphie B. - Massive (Airtight Remix) 045. Ralphie B - Demons Are Forever 046. Steve Brian - Yaya (Cressida Remix) 047. Max Graham & Susana - Down To Nothing (Johan Malmgren Remix) 048. Timur Adagio - Broken (Rave CHannel Remix) 049. D-Mad feat. Emma Lock - Counting On Love (Wellenrausch Remix) 050. Ana Criado & Ronski Speed - Afterglow (Will Holland Remix) 051. Ferry Corsten feat. Shelley Harland - Holding On (Above & Beyond Remix) 052. Pedro Del Mar - Midnight Sun (Illitheas Remix) 053. Rory Gallagher feat. Dawn - Remember Me (Dan Stone Breaks Remix) 054. Alex Kunnari feat. Emma Lock - You And Me (KhoMha & Julius Beat Remix) 055. Dennis Sheperd & Talla 2XLC - Two Worlds (Original Mix) 056. Pixl - Starlight (Original Mix) 057. Robbie Rivera feat. Jes - Turn It Around (David Solano & Landis Remix) 058. Solarstone - Touchstone (Elfsong Remix) 059. The Blizzard - Piercing The Fog (Original Mix) 060. Armin Van Buuren feat. Ana Criado - Suddenly Summer (Original Mix) 061. Matt Lange, Kerry Leva & Andrew Bayer - In And Out Of Phase (Club Edit) 062. Spark7 & Magdalene - Rebirth 063. Stone & Van Linden feat. Lyck - Into The Light (Festival Mix) 064. The Thrillseekers vs. M.I.K.E. - Effectual (Original Mix) 065. David Broaders - The Best Is Yet To Come (Solid Stone Remix) 066. Abstract Vision & Elite Electronic - Echoes (Protoculture Remix) 067. Paul Oakenfold - Glow In The Dark (Original Mix) 068. Ronski Speed feat. Stine Grove - Run To The Sunlight (Kyau & Albert Remix) 069. Solis & Sean Truby - Marina (Aaron Camz Remix) 070. Susana & Max Graham - Down To Nothing (Original Mix) 071. Orjan Nilsen feat. Neev Kennedy - Anywhere But Here 072. Tellur & Sound Quelle - Try Again (Original Mix) 073. Eon Wave - A Treasure 074. Mike Foyle & ReFeel - Universal Language (Original Mix) 075. Ronski Speed feat. Renee Stahl - Out Of Control (Dennis Sheperd Remix) 076. Arty - Vanilla Sky (Original Mix) 077. White Noise Machine - Empire (Super Hoo Men Remix) 078. Andain - Much Too Much (Mike Shiver Remix) 079. Alexander Popov - When The Sun (Eximinds Remix) 080. Facade & Q'Bass - Intensity (Q'Bass Mix) 081. John O'Callaghan & Kathryn Gallagher - Mess Of A Machine (Sean Tyas Remix) 082. Sied Van Riel - Tunnel Vision (Original Mix) 083. Styller - All That Remains (Original Mix) 084. Senadee - Life Support Machine (Richard Beynon Remix) 085. Acute - Terabyte (Original Mix) 086. Jer Martin - Ten Minutes To Midnight (Original Club Mix) 087. Poonyk & Oxide - Weekend (Alex Pich pres. Aleete Remix) 088. Ronny K. - White Rose 089. A.R.D.I. - Premonition (Original Mix) 090. Martin Etchegaray - Hunt The Clues (Rikesto SpaceVox Remix) 091. Temple One feat. Neev Kennedy - Love The Fear (Eximinds Remix) 092. Joey V - Laura Mae (Bobina Remix) 093. Ruby & Tony - Crema (Original Mix) 094. Arkane, Kane Nelson & Andre Van Reese - Bang! (Channel Surfer Remix) 095. Fast Distance - Alpine (Karanda Intro Remix) 096. Orkidea - Unity (Solarstone’s Pure Mix) 097. Sixma & Klauss Goulart feat. Outono Em Marte - Want To Fly (Ruby & Tony Remix) 098. Dreas vs. Alex Robert - Miramar (Original Mix) 099. Sean Tyas - Lifeat. (Lisa Lashes Remix) 100. Vast Vision feat. Fisher - Hurricane (Ost & Meyer Remix)

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